如何取得/轉換/剪接/合併自己上傳的 Youtube影片為 mp3

這篇文章,分成4個重點,取得/轉換/剪接/合併,還有分享如何幫mp3 檔案增加封面圖片。

最好的解法,還是使用有瀏覽器+擋廣告功能,在google 使用關鍵字:youtube mp3 download ,建議使用 yt1s 提供的服務來下載 mp3.


1:取得youtube 上的影片

透過 youtube-dl 指令,可以取得 youtube 上的影片。

2:轉換 youtube 上的影片為 mp3

這個功能,除了可以使用 youtube-dl 指令,一次直取得並轉換之外,如果你想要手機上取得youtube 上的影片為mp3, 也可以使用很多免費的網站,有提供線上下載的服務。

先在手機的YouTube 的官方 app 裡去輸入關鍵字,找到想要的歌曲或合輯。

再使用手機瀏覽器,在google 輸入關鍵字 youtube mp3 去查,然後在任一個查出來的網頁裡的輸入框裡貼上剛才YouTube 的網址,就可以開始轉換(或下載)該首歌的mp3 檔案在手機裡。

建議使用brave 瀏覽器來操作,會比較不會看到廣告,也可以使用brave瀏覽器去YouTube 網站,brave 瀏覽器除了可以背景播放音樂之外,而且還不會有廣告,超讚的!

透過手機備份自己所拍攝的影片很方便,如果想在電腦裡下載自己行上的影片,可以透過外部指令 youtube-dl + youtube 網址即可下載到自己上傳的影片,進而可以剪輯影片內容。


youtube-dl的指令,也可以把「自己上傳」到網路上的影片轉成 mp3:

youtube-dl -x --no-check-certificate --audio-format mp3 -f 'bestaudio[ext=m4a]' --embed-thumbnail --no-check-certificate <video URL>

如果覺得上面指令太長,就寫一個 shell script(批次檔)如下:

Mac OS/Linux:

#!/bin/bash
youtube-dl -x --no-check-certificate --audio-format mp3 -f 'bestaudio[ext=m4a]' --embed-thumbnail --no-check-certificate ${1}

Windows

@youtube-dl -x --no-check-certificate --audio-format mp3 -f 'bestaudio[ext=m4a]' --embed-thumbnail --no-check-certificate %1

Linux 之下,要記得執行:

chmod +x dl.sh

這樣子,檔案才能被執行。


youtube-dl 的關於解碼聲音的說:

Post-processing Options:
 -x, --extract-audio Convert video files to audio-only files (requires ffmpeg or avconv and
 ffprobe or avprobe)
 --audio-format FORMAT Specify audio format: "best", "aac", "flac", "mp3", "m4a", "opus",
 "vorbis", or "wav"; "best" by default; No effect without -x
 --audio-quality QUALITY Specify ffmpeg/avconv audio quality, insert a value between 0 (better)
 and 9 (worse) for VBR or a specific bitrate like 128K (default 5)

建議的作法:(以 Mac OS X 為例)

1: 安裝 youtube-dl
https://rg3.github.io/youtube-dl/download.html

brew install youtube-dl

使用方法:

youtube-dl + URL

附註:

youtube-dl 比你想像中的還強,除了可以備份自己上傳到 youtube 或 facebook 之外,你所上傳到其他知名「影音」網站上公開的影片都可以備份下載。

2:安裝 ffmpeg
https://www.ffmpeg.org/download.html

brew install ffmpeg

使用方法:

ffmpeg -i input.mp4 output.mp3

附註:由於 ffmpeg 和 youtube 定前都會更新版本,所以建議遇到有問題的時候,先升級到最新版本試看看,更新方法:

brew update
brew upgrade

錯誤排除的方法,如果遇到顯示這個錯誤:

[debug] ffmpeg command line: ffprobe -show_streams ‘file:The Chainsmokers 老菸槍 & Coldplay 酷玩樂團 _. Something Just Like This  如此而已 中文字幕-WslMtygxznQ.mp4’

ERROR: WARNING: unable to obtain file audio codec with ffprobe

請先下指令:

youtube-dl -v -x URL

透過-v 參數來輸出 debug 資訊,可以看到實際下載的影片網址,結果點進去,真的就沒有聲音的版本,所以透過下列的指令,也無法把youtube-dl 下載下來的 mp4 轉成 mp3:

ffmpeg -i 檔名.mp4 檔名.mp3

如果想知道,youtube 上面提供了那一些的格式,可以使用指令:

youtube-dl -x --no-check-certificate -F URL

結果:

[info] Available formats for WslMtygxznQ:
 format code  extension  resolution note
 249          webm       audio only DASH audio   60k , opus @ 50k, 1.47MiB
 250          webm       audio only DASH audio   78k , opus @ 70k, 1.95MiB
 140          m4a        audio only DASH audio  128k , m4a_dash container, mp4a.40.2@128k, 3.75MiB
 394          mp4        audio only 144p  134k , 30fps, 1.80MiB
 171          webm       audio only DASH audio  137k , vorbis@128k, 3.78MiB
 251          webm       audio only DASH audio  144k , opus @160k, 3.83MiB
 395          mp4        audio only 240p  152k , 30fps, 1.72MiB
 396          mp4        audio only 360p  252k , 30fps, 2.97MiB
 397          mp4        audio only 480p  391k , 30fps, 4.93MiB
 398          mp4        audio only 720p  772k , 30fps, 11.77MiB
 160          mp4        256x144    144p   41k , avc1.4d400c, 30fps, video only, 859.74KiB
 278          webm       256x144    144p   91k , webm container, vp9, 30fps, video only, 2.19MiB
 133          mp4        426x240    240p   95k , avc1.4d4015, 30fps, video only, 1.80MiB
 242          webm       426x240    240p  119k , vp9, 30fps, video only, 2.29MiB
 134          mp4        640x360    360p  188k , avc1.4d401e, 30fps, video only, 3.71MiB
 243          webm       640x360    360p  213k , vp9, 30fps, video only, 4.06MiB
 244          webm       854x480    480p  309k , vp9, 30fps, video only, 6.18MiB
 135          mp4        854x480    480p  317k , avc1.4d401f, 30fps, video only, 6.04MiB
 136          mp4        1280x720   720p  594k , avc1.4d401f, 30fps, video only, 10.78MiB
 247          webm       1280x720   720p  601k , vp9, 30fps, video only, 10.37MiB
 18           mp4        640x360    medium , avc1.42001E, mp4a.40.2@ 96k, 10.63MiB (best)

可以發現,畫質最佳的 1280×720 webm 格式是沒有聲音的,也是造成預設參數的情況下,取得無聲影片的結果。

-F 會列出所以格式(format code),-f 是去下載特定的格式。如果想要下載特定的格式。


.mp3 轉成 .amr

透過 ffmpeg 也可以把聲音轉換為 .amr 格式。

The Adaptive Multi-Rate (AMR) codec is an audio compression format enhanced for speech coding.
https://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec

只是透過 ffmpeg 所轉換的 .amr sample rate “只有” 8000, 音質快吐血,而且只支援單聲道。轉成 .amr 的指令:

ffmpeg -i mfile.mp3 -ar 8000 -ac 1 audio.amr

下面是 youtube-dl 的官方英文說明:

FORMAT SELECTION

By default youtube-dl tries to download the best available quality, i.e. if you want the best quality you don’t need to pass any special options, youtube-dl will guess it for you by default.

But sometimes you may want to download in a different format, for example when you are on a slow or intermittent connection. The key mechanism for achieving this is so-called format selection based on which you can explicitly specify desired format, select formats based on some criterion or criteria, setup precedence and much more.

The general syntax for format selection is --format FORMAT or shorter -f FORMAT where FORMAT is a selector expression, i.e. an expression that describes format or formats you would like to download.

tl;dr: navigate me to examples.

The simplest case is requesting a specific format, for example with -f 22 you can download the format with format code equal to 22. You can get the list of available format codes for particular video using --list-formats or -F. Note that these format codes are extractor specific.

You can also use a file extension (currently 3gpaacflvm4amp3mp4oggwavwebm are supported) to download the best quality format of a particular file extension served as a single file, e.g. -f webm will download the best quality format with the webm extension served as a single file.

You can also use special names to select particular edge case formats:

  • best: Select the best quality format represented by a single file with video and audio.
  • worst: Select the worst quality format represented by a single file with video and audio.
  • bestvideo: Select the best quality video-only format (e.g. DASH video). May not be available.
  • worstvideo: Select the worst quality video-only format. May not be available.
  • bestaudio: Select the best quality audio only-format. May not be available.
  • worstaudio: Select the worst quality audio only-format. May not be available.

For example, to download the worst quality video-only format you can use -f worstvideo.

If you want to download multiple videos and they don’t have the same formats available, you can specify the order of preference using slashes. Note that slash is left-associative, i.e. formats on the left hand side are preferred, for example -f 22/17/18 will download format 22 if it’s available, otherwise it will download format 17 if it’s available, otherwise it will download format 18 if it’s available, otherwise it will complain that no suitable formats are available for download.

If you want to download several formats of the same video use a comma as a separator, e.g. -f 22,17,18 will download all these three formats, of course if they are available. Or a more sophisticated example combined with the precedence feature: -f 136/137/mp4/bestvideo,140/m4a/bestaudio.

You can also filter the video formats by putting a condition in brackets, as in -f "best[height=720]" (or -f "[filesize>10M]").

The following numeric meta fields can be used with comparisons <<=>>== (equals), != (not equals):

  • filesize: The number of bytes, if known in advance
  • width: Width of the video, if known
  • height: Height of the video, if known
  • tbr: Average bitrate of audio and video in KBit/s
  • abr: Average audio bitrate in KBit/s
  • vbr: Average video bitrate in KBit/s
  • asr: Audio sampling rate in Hertz
  • fps: Frame rate

Also filtering work for comparisons = (equals), ^= (starts with), $= (ends with), *= (contains) and following string meta fields:

  • ext: File extension
  • acodec: Name of the audio codec in use
  • vcodec: Name of the video codec in use
  • container: Name of the container format
  • protocol: The protocol that will be used for the actual download, lower-case (httphttpsrtsprtmprtmpemmsf4mismhttp_dash_segmentsm3u8, or m3u8_native)
  • format_id: A short description of the format

Any string comparison may be prefixed with negation ! in order to produce an opposite comparison, e.g. !*= (does not contain).

Note that none of the aforementioned meta fields are guaranteed to be present since this solely depends on the metadata obtained by particular extractor, i.e. the metadata offered by the video hoster.

Formats for which the value is not known are excluded unless you put a question mark (?) after the operator. You can combine format filters, so -f "[height <=? 720][tbr>500]" selects up to 720p videos (or videos where the height is not known) with a bitrate of at least 500 KBit/s.

You can merge the video and audio of two formats into a single file using -f <video-format>+<audio-format>(requires ffmpeg or avconv installed), for example -f bestvideo+bestaudio will download the best video-only format, the best audio-only format and mux them together with ffmpeg/avconv.

Format selectors can also be grouped using parentheses, for example if you want to download the best mp4 and webm formats with a height lower than 480 you can use -f '(mp4,webm)[height<480]'.

Since the end of April 2015 and version 2015.04.26, youtube-dl uses -f bestvideo+bestaudio/best as the default format selection (see #5447#5456). If ffmpeg or avconv are installed this results in downloading bestvideo and bestaudio separately and muxing them together into a single file giving the best overall quality available. Otherwise it falls back to best and results in downloading the best available quality served as a single file. best is also needed for videos that don’t come from YouTube because they don’t provide the audio and video in two different files. If you want to only download some DASH formats (for example if you are not interested in getting videos with a resolution higher than 1080p), you can add -f bestvideo[height<=?1080]+bestaudio/best to your configuration file. Note that if you use youtube-dl to stream to stdout (and most likely to pipe it to your media player then), i.e. you explicitly specify output template as -o -, youtube-dl still uses -f best format selection in order to start content delivery immediately to your player and not to wait until bestvideo and bestaudio are downloaded and muxed.

If you want to preserve the old format selection behavior (prior to youtube-dl 2015.04.26), i.e. you want to download the best available quality media served as a single file, you should explicitly specify your choice with -f best. You may want to add it to the configuration file in order not to type it every time you run youtube-dl.

Format selection examples

Note that on Windows you may need to use double quotes instead of single.

# Download best mp4 format available or any other best if no mp4 available
$ youtube-dl -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best'

# Download best format available but no better than 480p
$ youtube-dl -f 'bestvideo[height<=480]+bestaudio/best[height<=480]'

# Download best video only format but no bigger than 50 MB
$ youtube-dl -f 'best[filesize<50M]'

# Download best format available via direct link over HTTP/HTTPS protocol
$ youtube-dl -f '(bestvideo+bestaudio/best)[protocol^=http]'

# Download the best video format and the best audio format without merging them
$ youtube-dl -f 'bestvideo,bestaudio' -o '%(title)s.f%(format_id)s.%(ext)s'

Note that in the last example, an output template is recommended as bestvideo and bestaudio may have the same file name.


3:剪接 mp3

我們想要取影片中的一小段時… 可以利用ffmpeg下個指令就好了

ffmpeg -ss 00:20:48.500 -t 00:01:00 -i INPUT.mp4 OUTPUT.mp4
  • -ss 是指影片的第幾分幾秒開始剪
  • -t 是指要剪多少時間, 如果不使用就會直接到檔案最後。
  • -acodec copy -vcodec copy 這個參數不是預設值,沒有下的話會變成預設的編碼,會很慢。

較佳解法:

ffmpeg -ss 開始時間 -t 長度 -i 原來檔案.mp4 -acodec copy -vcodec copy 輸出檔案.mp4

服用了參數 -acodec copy -vcodec copy ,剪接即使是 2~3小時的mp3,幾乎都是一秒內搞定。如果來源檔是mp3就不用加上面這個參數,反正一下子就處理完了,是為了要處理超長的影片才需要使用。

附註:-acode copy 的參數,要「夾在」第二個檔案的前面,沒辦法在最前面加,或加在最後面,這一點有點怪怪的!


範例1:直接全部內容轉mp3

ffmpeg -i video.mp4 audio.mp3

範例2:mp3第10秒起,剪下6秒

ffmpeg -ss 10 -i input.mp3 -t 6 output.mp3

範例3:mp3去掉前30秒

ffmpeg -ss 30 -i inputfile.mp3 outputfile.mp3

-ss 是指影片的第幾分幾秒開始剪
-t 是指要剪多少時間

要去掉尾部的秒數,直接使用 -t 參數。

範例4:mp3 增加縮圖

詳細用法參考:
https://www.ffmpeg.org/ffmpeg.html#toc-Main-options

ffmpeg -i in.mp3 -i in.jpg -map 1 -map 0 -c copy -disposition:0 attached_pic out.mp3

如果想要取得youtube 影片的縮圖,可以google 關鍵字 download youtube thumbnail ,有很多類似服務的網站,例如:
https://youtube-thumbnail-grabber.com/


例如我有一部影片檔案大小 4.7GB 要分割成 2個小檔案,所以分別執行下面二行指令即可完成任務:

  • 前1小時,切成一個獨立檔案: ffmpeg -t 01:00:00 -i 蟻人1.Ant.Man.\(2015\).mp4 -acodec copy -vcodec copy output1.mp4
  • 第2個小時到最後,切成一個獨立檔案:
    ffmpeg -ss 01:00:00  -i 蟻人1.Ant.Man.\(2015\).mp4 -acodec copy -vcodec copy output2.mp4

剪輯多音軌範例:

# fmpeg -i input.mkv

ffmpeg version ... Copyright (c) 2000-2012 the FFmpeg developers
...
Input #0, matroska,webm, from 'input.mkv':
  Duration: 01:39:44.02, start: 0.000000, bitrate: 5793 kb/s
    Stream #0:0(eng): Video: h264 (High), yuv420p, 1920x800, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Stream #0:1(ger): Audio: dts (DTS), 48000 Hz, 5.1(side), s16, 1536 kb/s (default)
    Stream #0:2(eng): Audio: dts (DTS), 48000 Hz, 5.1(side), s16, 1536 kb/s
    Stream #0:3(ger): Subtitle: text (default)
At least one output file must be specified

Example 1

Now, let’s say we want to:

  • copy video stream
  • encode german audio stream to mp3 (128kbps) and aac (96kbps) (creating 2 audio streams in the output)
  • drop english audio stream
  • copy subtitle stream

This can be done using the following FFmpeg command line:

ffmpeg -i input.mkv \
    -map 0:0 -map 0:1 -map 0:1 -map 0:3 \
    -c:v copy \
    -c:a:0 libmp3lame -b:a:0 128k \
    -c:a:1 libfaac -b:a:1 96k \
    -c:s copy \
    output.mkv

Note there is no “-map 0:2” and that “-map 0:1” has been specified twice.

Using “-map 0:0 -map 0:1 -map 0:1 -map 0:3” we told FFmpeg to select/map specified input streams to output in that order.

So, our output will now have the following streams:

Output #0, matroska, to 'output.mkv':
    Stream #0:0(eng): Video ...
    Stream #0:1(ger): Audio ...
    Stream #0:2(ger): Audio ...
    Stream #0:3(ger): Subtitle ...

After we selected which streams we would like in our output, using “-map” option, we specified codecs for each stream in our output.

Video and subtitle stream have just been copied and german audio stream has been encoded to 2 new audio streams, mp3 and aac.

We used “-c:a:0” to specify codec for the output’s first AUDIO stream and “-c:a:1” to specify codec for the output’s second AUDIO stream.

Note that “a:0” refers to the output’s first AUDIO stream (#0:1 in our case), “a:1” refers to the output’s 2nd AUDIO stream (which is also mapped to the input stream #0:1), etc.

The result will be:

Output #0, matroska, to 'output.mkv':
    Stream #0:0(eng): Video ...
    Stream #0:1(ger): Audio ...
    Stream #0:2(ger): Audio ...
    Stream #0:3(ger): Subtitle ...
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (dca -> libmp3lame)
  Stream #0:2 -> #0:2 (dca -> libfaac)
  Stream #0:3 -> #0:3 (copy)

Example 2

Let’s say that we want to reorder input streams backwards, so that we have output like this:

    Stream #0:0(ger): Subtitle: text (default)
    Stream #0:1(eng): Audio: dts (DTS), 48000 Hz, 5.1(side), s16, 1536 kb/s
    Stream #0:2(ger): Audio: dts (DTS), 48000 Hz, 5.1(side), s16, 1536 kb/s (default)
    Stream #0:3(eng): Video: h264 (High), yuv420p, 1920x800, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)

This can simply be done using the following command line:

ffmpeg -i input.mkv -map 0:3 -map 0:2 -map 0:1 -map 0:0 -c copy output.mkv

Note that we specified all the input streams, but in the reverse order, which causes that order to be respected in the output.

The option “-c copy” tells FFmpeg to use “copy” on all streams.


Example 3

If we want to extract only audio streams, from the same input file, then we can do it like this:

ffmpeg -i input.mkv -map 0:1 -map 0:2 -c copy output.mkv

Example 4

If we want to re-encode just the video streams, but copy all the other streams (like audio, subtitles, attachments, etc), we might use something like this:

ffmpeg -i input.mkv -map 0 -c copy -c:v mpeg2video output.mkv

It will tell ffmpeg to:

  • read the input file ‘input.mkv’
  • select all the input streams (first input = 0) to be processed (using “-map 0”)
  • mark all the streams to be just copied to the output (using “-c copy”)
  • mark just the video streams to be re-encoded (using “-c:v mpeg2video”)
  • write the output file ‘output.mkv’

Example 5

You can use the “-map” command in creating multiple output files, ex:

ffmpeg -i input.mkv -map 0:1 -map 0:2 audios_only.mkv -map 0:0 video_only.mkv

The default is to map the “highest quality video” and “highest quality audio” to each output file (basically reuses it for each output), see also Creating multiple outputs.


Example 6

You can use the named output of a filtergraph as a mapping parameter, ex:

ffmpeg -i INPUT -filter_complex "[0] scale=100x100[smaller_sized]"  -map "[smaller_sized]" out.mp4

which (in our example) is the same as specifying the stream more precisely, and equivalent to this

ffmpeg -i INPUT -filter_complex "[0:0] scale=100x100[smaller_sized]"  -map "[smaller_sized]" out.mp4

Example 7

There are stream selection shortcuts you can also use like “0:v”

ffmpeg -i input -map 0:v -map 0:a output.mkv # chooses video and audio from input 0

See ​stream specifiers for details.


Example 8

MPEG stream selection:

The tricky part with selecting from MPEG TS is it may contain multiple streams/channels, and if you are receiving “live data” just specifying an index might not work because it can change from run to run, so

ffmpeg -i INPUT -map 0:6 OUTPUT # might not work the same every run, DO NOT USE THIS WAY!

Assuming your file is MPEG, you can run “ffmpeg -i INPUT” (not specify an output) to see what program id’s and stream id’s it contains, like this example (probesize and analyzeduration specified to help “make sure” it picks up all the streams in it, may not be always needed)

$ ffmpeg -probesize 50M -analyzeduration 50M -i INPUT
...
Input #0, mpegts, from 'INPUT':
  Duration: N/A, start: 22159.226833, bitrate: N/A
  Program 1344
    Metadata:
      service_name    : 7 Digital
      service_provider: Seven Network
    Stream #0:0[0x401]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], max. 14950 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x402](eng): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, s16p, 256 kb/s
  Program 1346
    Metadata:
      service_name    : 7TWO
      service_provider: Seven Network
    Stream #0:3[0x406]: Unknown: none ([5][0][0][0] / 0x0005)
    Stream #0:6[0x421]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], max. 14950 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:7[0x422](eng): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, s16p, 192 kb/s
    Stream #0:8[0x424](eng): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006), 492x250
    Stream #0:4[0x499]: Unknown: none ([11][0][0][0] / 0x000B)

you could specify desired streams by program id:

ffmpeg -i INPUT -map 0:p:1344 OUTPUT # pulls in both inputs from program 1344, channel "7 Digital" in this case

or specify a child stream:

ffmpeg -i INPUT -map i:0x401 OUTPUT # pulls in the single input stream with PID (MPEG Packet ID [stream identifier]) 0x401 from wherever it is found, in this case its a video stream in "7 Digital"

or similar, see other specifier examples. Note if you have “unknown” streams in there you may need to add the -ignore_unknown flag as well.

Also note that if your input stream contains multiple program id’s, you can record simultaneously from various of them, using the same FFmpeg instance and the map commands described here.


Example 9

Include “all” inputs to the output. The default behavior is to copy only one audio and one video channel. If you want to copy ‘all’ channels, use “-map”

# re encodes all video and audio channels from input one
ffmpeg -i input -map 0 output.mp4 

# copies all video and audio channels from input one to output, not just one video
ffmpeg -i input -map 0 -c copy output.mp4 

範例9 號滿實用的,因為使用參數:-acodec copy -vcodec copy 只會輸出第一個音軌, 如果使用 -map 0 -c copy 則可以輸出所有音軌出來。

要知道多媒體檔案的資訊,可以「不放輸出檔案的參數」,即可取得所有 stream 的資訊。


轉檔,透過 bitrate 縮小檔案:

The typical example would be something like this:

ffmpeg -i input -c:v libx264 -b:v 2M -maxrate 2M -bufsize 1M output.mp4

由於youtube 會有很多個編碼格式,youtube-dl 可能猜測的不是最佳的,或是最佳的格式並不適合你的播放器,你可以先用參數 –list-formats (或使用 -F)去取得最佳格式:

--list-formats

針對 resolution note 選取偏愛的 format code 再使用參數 –format (或使用 -f)去取得影片:

--format

增加音軌到影片檔案:

FFMPEG add additional audio track in video (mix 2 audio)

ffmpeg -i video.mp4 -i audio.wav -c:v copy -c:a copy -strict experimental output.mp4

Here, we assume that the video file does not contain any audio stream yet, and that you want to have the same output format (here, MP4) as the input format.

The above command transcodes the audio, since MP4s cannot carry PCM audio streams. You can use any other desired audio codec if you want. See the AAC Encoding Guide for more info.

If your audio or video stream is longer, you can add the -shortest option so that ffmpeg will stop encoding once one file ends.


Copying the audio without re-encoding

If your output container can handle (almost) any codec – like MKV – then you can simply copy both audio and video streams:

ffmpeg -i video.mp4 -i audio.wav -c copy output.mkv

Replacing audio stream

If your input video already contains audio, and you want to replace it, you need to tell ffmpeg which audio stream to take:

ffmpeg -i video.mp4 -i audio.wav \
-c:v copy -c:a aac -strict experimental \
-map 0:v:0 -map 1:a:0 output.mp4

The map option makes ffmpeg only use the first video stream from the first input and the first audio stream from the second input for the output file.


附註 youtube-dl 完整參數:

https://github.com/rg3/youtube-dl/blob/master/README.md#options

youtube-dl is a command-line program to download videos from YouTube.com and a few more sites. It requires the Python interpreter, version 2.6, 2.7, or 3.2+, and it is not platform specific. It should work on your Unix box, on Windows or on Mac OS X. It is released to the public domain, which means you can modify it, redistribute it or use it however you like.

youtube-dl [OPTIONS] URL [URL...]

OPTIONS

-h, --help                       Print this help text and exit
--version                        Print program version and exit
-U, --update                     Update this program to latest version. Make
                                 sure that you have sufficient permissions
                                 (run with sudo if needed)
-i, --ignore-errors              Continue on download errors, for example to
                                 skip unavailable videos in a playlist
--abort-on-error                 Abort downloading of further videos (in the
                                 playlist or the command line) if an error
                                 occurs
--dump-user-agent                Display the current browser identification
--list-extractors                List all supported extractors
--extractor-descriptions         Output descriptions of all supported
                                 extractors
--force-generic-extractor        Force extraction to use the generic
                                 extractor
--default-search PREFIX          Use this prefix for unqualified URLs. For
                                 example "gvsearch2:" downloads two videos
                                 from google videos for youtube-dl "large
                                 apple". Use the value "auto" to let
                                 youtube-dl guess ("auto_warning" to emit a
                                 warning when guessing). "error" just throws
                                 an error. The default value "fixup_error"
                                 repairs broken URLs, but emits an error if
                                 this is not possible instead of searching.
--ignore-config                  Do not read configuration files. When given
                                 in the global configuration file
                                 /etc/youtube-dl.conf: Do not read the user
                                 configuration in ~/.config/youtube-
                                 dl/config (%APPDATA%/youtube-dl/config.txt
                                 on Windows)
--config-location PATH           Location of the configuration file; either
                                 the path to the config or its containing
                                 directory.
--flat-playlist                  Do not extract the videos of a playlist,
                                 only list them.
--mark-watched                   Mark videos watched (YouTube only)
--no-mark-watched                Do not mark videos watched (YouTube only)
--no-color                       Do not emit color codes in output

Network Options:

--proxy URL                      Use the specified HTTP/HTTPS/SOCKS proxy.
                                 To enable experimental SOCKS proxy, specify
                                 a proper scheme. For example
                                 socks5://127.0.0.1:1080/. Pass in an empty
                                 string (--proxy "") for direct connection
--socket-timeout SECONDS         Time to wait before giving up, in seconds
--source-address IP              Client-side IP address to bind to
-4, --force-ipv4                 Make all connections via IPv4
-6, --force-ipv6                 Make all connections via IPv6

Geo Restriction:

--geo-verification-proxy URL     Use this proxy to verify the IP address for
                                 some geo-restricted sites. The default
                                 proxy specified by --proxy (or none, if the
                                 options is not present) is used for the
                                 actual downloading.
--geo-bypass                     Bypass geographic restriction via faking
                                 X-Forwarded-For HTTP header (experimental)
--no-geo-bypass                  Do not bypass geographic restriction via
                                 faking X-Forwarded-For HTTP header
                                 (experimental)
--geo-bypass-country CODE        Force bypass geographic restriction with
                                 explicitly provided two-letter ISO 3166-2
                                 country code (experimental)

Video Selection:

--playlist-start NUMBER          Playlist video to start at (default is 1)
--playlist-end NUMBER            Playlist video to end at (default is last)
--playlist-items ITEM_SPEC       Playlist video items to download. Specify
                                 indices of the videos in the playlist
                                 separated by commas like: "--playlist-items
                                 1,2,5,8" if you want to download videos
                                 indexed 1, 2, 5, 8 in the playlist. You can
                                 specify range: "--playlist-items
                                 1-3,7,10-13", it will download the videos
                                 at index 1, 2, 3, 7, 10, 11, 12 and 13.
--match-title REGEX              Download only matching titles (regex or
                                 caseless sub-string)
--reject-title REGEX             Skip download for matching titles (regex or
                                 caseless sub-string)
--max-downloads NUMBER           Abort after downloading NUMBER files
--min-filesize SIZE              Do not download any videos smaller than
                                 SIZE (e.g. 50k or 44.6m)
--max-filesize SIZE              Do not download any videos larger than SIZE
                                 (e.g. 50k or 44.6m)
--date DATE                      Download only videos uploaded in this date
--datebefore DATE                Download only videos uploaded on or before
                                 this date (i.e. inclusive)
--dateafter DATE                 Download only videos uploaded on or after
                                 this date (i.e. inclusive)
--min-views COUNT                Do not download any videos with less than
                                 COUNT views
--max-views COUNT                Do not download any videos with more than
                                 COUNT views
--match-filter FILTER            Generic video filter. Specify any key (see
                                 the "OUTPUT TEMPLATE" for a list of
                                 available keys) to match if the key is
                                 present, !key to check if the key is not
                                 present, key > NUMBER (like "comment_count
                                 > 12", also works with >=, <, <=, !=, =) to
                                 compare against a number, key = 'LITERAL'
                                 (like "uploader = 'Mike Smith'", also works
                                 with !=) to match against a string literal
                                 and & to require multiple matches. Values
                                 which are not known are excluded unless you
                                 put a question mark (?) after the operator.
                                 For example, to only match videos that have
                                 been liked more than 100 times and disliked
                                 less than 50 times (or the dislike
                                 functionality is not available at the given
                                 service), but who also have a description,
                                 use --match-filter "like_count > 100 &
                                 dislike_count <? 50 & description" .
--no-playlist                    Download only the video, if the URL refers
                                 to a video and a playlist.
--yes-playlist                   Download the playlist, if the URL refers to
                                 a video and a playlist.
--age-limit YEARS                Download only videos suitable for the given
                                 age
--download-archive FILE          Download only videos not listed in the
                                 archive file. Record the IDs of all
                                 downloaded videos in it.
--include-ads                    Download advertisements as well
                                 (experimental)

Download Options:

-r, --limit-rate RATE            Maximum download rate in bytes per second
                                 (e.g. 50K or 4.2M)
-R, --retries RETRIES            Number of retries (default is 10), or
                                 "infinite".
--fragment-retries RETRIES       Number of retries for a fragment (default
                                 is 10), or "infinite" (DASH, hlsnative and
                                 ISM)
--skip-unavailable-fragments     Skip unavailable fragments (DASH, hlsnative
                                 and ISM)
--abort-on-unavailable-fragment  Abort downloading when some fragment is not
                                 available
--keep-fragments                 Keep downloaded fragments on disk after
                                 downloading is finished; fragments are
                                 erased by default
--buffer-size SIZE               Size of download buffer (e.g. 1024 or 16K)
                                 (default is 1024)
--no-resize-buffer               Do not automatically adjust the buffer
                                 size. By default, the buffer size is
                                 automatically resized from an initial value
                                 of SIZE.
--playlist-reverse               Download playlist videos in reverse order
--playlist-random                Download playlist videos in random order
--xattr-set-filesize             Set file xattribute ytdl.filesize with
                                 expected file size (experimental)
--hls-prefer-native              Use the native HLS downloader instead of
                                 ffmpeg
--hls-prefer-ffmpeg              Use ffmpeg instead of the native HLS
                                 downloader
--hls-use-mpegts                 Use the mpegts container for HLS videos,
                                 allowing to play the video while
                                 downloading (some players may not be able
                                 to play it)
--external-downloader COMMAND    Use the specified external downloader.
                                 Currently supports
                                 aria2c,avconv,axel,curl,ffmpeg,httpie,wget
--external-downloader-args ARGS  Give these arguments to the external
                                 downloader

Filesystem Options:

-a, --batch-file FILE            File containing URLs to download ('-' for
                                 stdin)
--id                             Use only video ID in file name
-o, --output TEMPLATE            Output filename template, see the "OUTPUT
                                 TEMPLATE" for all the info
--autonumber-start NUMBER        Specify the start value for %(autonumber)s
                                 (default is 1)
--restrict-filenames             Restrict filenames to only ASCII
                                 characters, and avoid "&" and spaces in
                                 filenames
-w, --no-overwrites              Do not overwrite files
-c, --continue                   Force resume of partially downloaded files.
                                 By default, youtube-dl will resume
                                 downloads if possible.
--no-continue                    Do not resume partially downloaded files
                                 (restart from beginning)
--no-part                        Do not use .part files - write directly
                                 into output file
--no-mtime                       Do not use the Last-modified header to set
                                 the file modification time
--write-description              Write video description to a .description
                                 file
--write-info-json                Write video metadata to a .info.json file
--write-annotations              Write video annotations to a
                                 .annotations.xml file
--load-info-json FILE            JSON file containing the video information
                                 (created with the "--write-info-json"
                                 option)
--cookies FILE                   File to read cookies from and dump cookie
                                 jar in
--cache-dir DIR                  Location in the filesystem where youtube-dl
                                 can store some downloaded information
                                 permanently. By default
                                 $XDG_CACHE_HOME/youtube-dl or
                                 ~/.cache/youtube-dl . At the moment, only
                                 YouTube player files (for videos with
                                 obfuscated signatures) are cached, but that
                                 may change.
--no-cache-dir                   Disable filesystem caching
--rm-cache-dir                   Delete all filesystem cache files

Thumbnail images:

--write-thumbnail                Write thumbnail image to disk
--write-all-thumbnails           Write all thumbnail image formats to disk
--list-thumbnails                Simulate and list all available thumbnail
                                 formats

Verbosity / Simulation Options:

-q, --quiet                      Activate quiet mode
--no-warnings                    Ignore warnings
-s, --simulate                   Do not download the video and do not write
                                 anything to disk
--skip-download                  Do not download the video
-g, --get-url                    Simulate, quiet but print URL
-e, --get-title                  Simulate, quiet but print title
--get-id                         Simulate, quiet but print id
--get-thumbnail                  Simulate, quiet but print thumbnail URL
--get-description                Simulate, quiet but print video description
--get-duration                   Simulate, quiet but print video length
--get-filename                   Simulate, quiet but print output filename
--get-format                     Simulate, quiet but print output format
-j, --dump-json                  Simulate, quiet but print JSON information.
                                 See the "OUTPUT TEMPLATE" for a description
                                 of available keys.
-J, --dump-single-json           Simulate, quiet but print JSON information
                                 for each command-line argument. If the URL
                                 refers to a playlist, dump the whole
                                 playlist information in a single line.
--print-json                     Be quiet and print the video information as
                                 JSON (video is still being downloaded).
--newline                        Output progress bar as new lines
--no-progress                    Do not print progress bar
--console-title                  Display progress in console titlebar
-v, --verbose                    Print various debugging information
--dump-pages                     Print downloaded pages encoded using base64
                                 to debug problems (very verbose)
--write-pages                    Write downloaded intermediary pages to
                                 files in the current directory to debug
                                 problems
--print-traffic                  Display sent and read HTTP traffic
-C, --call-home                  Contact the youtube-dl server for debugging
--no-call-home                   Do NOT contact the youtube-dl server for
                                 debugging

Workarounds:

--encoding ENCODING              Force the specified encoding (experimental)
--no-check-certificate           Suppress HTTPS certificate validation
--prefer-insecure                Use an unencrypted connection to retrieve
                                 information about the video. (Currently
                                 supported only for YouTube)
--user-agent UA                  Specify a custom user agent
--referer URL                    Specify a custom referer, use if the video
                                 access is restricted to one domain
--add-header FIELD:VALUE         Specify a custom HTTP header and its value,
                                 separated by a colon ':'. You can use this
                                 option multiple times
--bidi-workaround                Work around terminals that lack
                                 bidirectional text support. Requires bidiv
                                 or fribidi executable in PATH
--sleep-interval SECONDS         Number of seconds to sleep before each
                                 download when used alone or a lower bound
                                 of a range for randomized sleep before each
                                 download (minimum possible number of
                                 seconds to sleep) when used along with
                                 --max-sleep-interval.
--max-sleep-interval SECONDS     Upper bound of a range for randomized sleep
                                 before each download (maximum possible
                                 number of seconds to sleep). Must only be
                                 used along with --min-sleep-interval.

Video Format Options:

-f, --format FORMAT              Video format code, see the "FORMAT
                                 SELECTION" for all the info
--all-formats                    Download all available video formats
--prefer-free-formats            Prefer free video formats unless a specific
                                 one is requested
-F, --list-formats               List all available formats of requested
                                 videos
--youtube-skip-dash-manifest     Do not download the DASH manifests and
                                 related data on YouTube videos
--merge-output-format FORMAT     If a merge is required (e.g.
                                 bestvideo+bestaudio), output to given
                                 container format. One of mkv, mp4, ogg,
                                 webm, flv. Ignored if no merge is required

Subtitle Options:

--write-sub                      Write subtitle file
--write-auto-sub                 Write automatically generated subtitle file
                                 (YouTube only)
--all-subs                       Download all the available subtitles of the
                                 video
--list-subs                      List all available subtitles for the video
--sub-format FORMAT              Subtitle format, accepts formats
                                 preference, for example: "srt" or
                                 "ass/srt/best"
--sub-lang LANGS                 Languages of the subtitles to download
                                 (optional) separated by commas, use --list-
                                 subs for available language tags

Authentication Options:

-u, --username USERNAME          Login with this account ID
-p, --password PASSWORD          Account password. If this option is left
                                 out, youtube-dl will ask interactively.
-2, --twofactor TWOFACTOR        Two-factor authentication code
-n, --netrc                      Use .netrc authentication data
--video-password PASSWORD        Video password (vimeo, smotri, youku)

Adobe Pass Options:

--ap-mso MSO                     Adobe Pass multiple-system operator (TV
                                 provider) identifier, use --ap-list-mso for
                                 a list of available MSOs
--ap-username USERNAME           Multiple-system operator account login
--ap-password PASSWORD           Multiple-system operator account password.
                                 If this option is left out, youtube-dl will
                                 ask interactively.
--ap-list-mso                    List all supported multiple-system
                                 operators

Post-processing Options:

-x, --extract-audio              Convert video files to audio-only files
                                 (requires ffmpeg or avconv and ffprobe or
                                 avprobe)
--audio-format FORMAT            Specify audio format: "best", "aac",
                                 "flac", "mp3", "m4a", "opus", "vorbis", or
                                 "wav"; "best" by default; No effect without
                                 -x
--audio-quality QUALITY          Specify ffmpeg/avconv audio quality, insert
                                 a value between 0 (better) and 9 (worse)
                                 for VBR or a specific bitrate like 128K
                                 (default 5)
--recode-video FORMAT            Encode the video to another format if
                                 necessary (currently supported:
                                 mp4|flv|ogg|webm|mkv|avi)
--postprocessor-args ARGS        Give these arguments to the postprocessor
-k, --keep-video                 Keep the video file on disk after the post-
                                 processing; the video is erased by default
--no-post-overwrites             Do not overwrite post-processed files; the
                                 post-processed files are overwritten by
                                 default
--embed-subs                     Embed subtitles in the video (only for mp4,
                                 webm and mkv videos)
--embed-thumbnail                Embed thumbnail in the audio as cover art
--add-metadata                   Write metadata to the video file
--metadata-from-title FORMAT     Parse additional metadata like song title /
                                 artist from the video title. The format
                                 syntax is the same as --output. Regular
                                 expression with named capture groups may
                                 also be used. The parsed parameters replace
                                 existing values. Example: --metadata-from-
                                 title "%(artist)s - %(title)s" matches a
                                 title like "Coldplay - Paradise". Example
                                 (regex): --metadata-from-title
                                 "(?P<artist>.+?) - (?P<title>.+)"
--xattrs                         Write metadata to the video file's xattrs
                                 (using dublin core and xdg standards)
--fixup POLICY                   Automatically correct known faults of the
                                 file. One of never (do nothing), warn (only
                                 emit a warning), detect_or_warn (the
                                 default; fix file if we can, warn
                                 otherwise)
--prefer-avconv                  Prefer avconv over ffmpeg for running the
                                 postprocessors (default)
--prefer-ffmpeg                  Prefer ffmpeg over avconv for running the
                                 postprocessors
--ffmpeg-location PATH           Location of the ffmpeg/avconv binary;
                                 either the path to the binary or its
                                 containing directory.
--exec CMD                       Execute a command on the file after
                                 downloading, similar to find's -exec
                                 syntax. Example: --exec 'adb push {}
                                 /sdcard/Music/ && rm {}'
--convert-subs FORMAT            Convert the subtitles to other format
                                 (currently supported: srt|ass|vtt)

如果遇到下面的錯誤訊息:

WARNING: Unable to download webpage: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1123)>
[youtube] aa2AhDaK_iY: Downloading API JSON
ERROR: Unable to download API page: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1123)> (caused by URLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1123)')))

解法:增加參數 –no-check-certificate

dd the no-check-certificate parameter to the command:

youtube-dl --no-check-certificate

資料來源:
https://stackoverflow.com/questions/60158087/youtubedl-certificate-verify-failed


4: 合併mp3

比較簡單的作法是建立一個文字檔,內容如下:

file '/path/to/first.mp3'
file '/path/to/second.mp3'

再服用 ffmpeg 指令,就可以合併成單一 mp3 檔案:

ffmpeg -f concat -i list.txt -c copy out.mp3

附註:文字檔不太能使用中文及emoji,建議改用英文或數字,就會沒問題,錯誤訊息如下:

[concat @ 0x7ffae7013a00] Unsafe file name 'A-Lin -《千尋》(電視劇《千古玦塵》插曲)🎵『無損高音質|CC歌詞字幕』-VE3p6-IGKG4.mp3'
list.txt: Operation not permitted

如果想要重新編碼(re-encoding)服用下面指令:

ffmpeg -i first.mp3 -i second.mp3 -filter_complex [0:a][1:a]concat=n=2:v=0:a=1 out.mp3

另一個範例,FFmpeg combine mp3 files to one mp3 file with delays

ffmpeg -i aaa.mp3 -i aab.mp3 -filter_complex "[0]adelay=10000|10000[a];[1]adelay=10000|10000[b];[a][b]amix=inputs=2" out.mp3

aaa.mp3 is input 0

aab.mp3 is input 1

[0]adelay=10000|10000[a]

Means take input 0 and add a delay of 10000milliseconds on both channel and name the stream specifier ‘a’

[1]adelay=10000|10000[b]

Take input 1 and add a delay of 10000milliseconds on both channel and the stream specifier ‘b’

[a][b]amix=inputs=2

mix the stream specifier called ‘a’ and ‘b’.

Here is a video that can help you to understand ffmpeg filter graph. https://youtu.be/hElDsyuAQDA?t=341

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