我正在尝试以编程方式下载YouTube 视频的一部分。广为人知的程序不适用于某些视频，我想克服这种情况。
我正在尝试以编程方式下载YouTube 视频的一部分。如如何使用 youtube-dl 命令下载部分视频中所述？，您可以通过以下命令实现此目的。
#Converts a human-readable URL to longer URLs for internal use.
~ $ youtube-dl --get-url 'https://www.youtube.com/watch?v=POrfo478HRI'
https://r1---sn-3pm76n76.googlevideo.com/videoplayback?expire=1597593009&ei=UQE5X7bXEYqO4QLs17KACQ&ip=10.100.238.99&id=o-AD0HfadoeimIbuf9t8Anru5X9V7cER08YyOz4iKZOCHL&itag=299&aitags=133%2C134%2C135%2C136%2C137%2C160%2C242%2C243%2C244%2C247%2C248%2C278%2C298%2C299%2C302%2C303&source=youtube&requiressl=yes&mh=NV&mm=31%2C26&mn=sn-3pm76n76%2Csn-oguesnze&ms=au%2Conr&mv=m&mvi=1&pl=17&initcwndbps=908750&vprv=1&mime=video%2Fmp4&gir=yes&clen=9205054989&dur=17931.000&lmt=1597347724488304&mt=1597571322&fvip=1&keepalive=yes&fexp=23883098&c=WEB&txp=7316222&sparams=expire%2Cei%2Cip%2Cid%2Caitags%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRQIgYDqTm0CnLfG0kxsYNrAdtAUYB7alnowiaBArU8R5bBwCIQDeCRDJHFO_PWcnbeFaJvip80deuboN4Pi1x3eRhJBxlQ%3D%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRgIhAKTkyTIGVkbWWVx4lqFz77rOdG1FzkM5XuTnYOqtHT4oAiEA9u1R47jPz-mjj4DRXpqqqpUbfaFMW36KbG_pR2jovFM%3D&ratebypass=yes
https://r1---sn-3pm76n76.googlevideo.com/videoplayback?expire=1597593009&ei=UQE5X7bXEYqO4QLs17KACQ&ip=10.100.238.99&id=o-AD0HfadoeimIbuf9t8Anru5X9V7cER08YyOz4iKZOCHL&itag=251&source=youtube&requiressl=yes&mh=NV&mm=31%2C26&mn=sn-3pm76n76%2Csn-oguesnze&ms=au%2Conr&mv=m&mvi=1&pl=17&initcwndbps=908750&vprv=1&mime=audio%2Fwebm&gir=yes&clen=268945126&dur=17931.001&lmt=1597348111385641&mt=1597571322&fvip=1&keepalive=yes&fexp=23883098&c=WEB&txp=7311222&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRgIhAK8XGu3vHucHwqERZ7TQniuvKEd-NTbMkwZbu8EXJ5E3AiEAiS7OYFOcsIrD2xp-AJNzucj1H9ZKMlmkCl_sU7__dZo%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRgIhAKTkyTIGVkbWWVx4lqFz77rOdG1FzkM5XuTnYOqtHT4oAiEA9u1R47jPz-mjj4DRXpqqqpUbfaFMW36KbG_pR2jovFM%3D&ratebypass=yes
#Stores the result to a variable.
~ $ url_video_part='https://r1---sn-3pm76n76.googlevideo.com/videoplayback?expire=1597593009&ei=UQE5X7bXEYqO4QLs17KACQ&ip=10.100.238.99&id=o-AD0HfadoeimIbuf9t8Anru5X9V7cER08YyOz4iKZOCHL&itag=299&aitags=133%2C134%2C135%2C136%2C137%2C160%2C242%2C243%2C244%2C247%2C248%2C278%2C298%2C299%2C302%2C303&source=youtube&requiressl=yes&mh=NV&mm=31%2C26&mn=sn-3pm76n76%2Csn-oguesnze&ms=au%2Conr&mv=m&mvi=1&pl=17&initcwndbps=908750&vprv=1&mime=video%2Fmp4&gir=yes&clen=9205054989&dur=17931.000&lmt=1597347724488304&mt=1597571322&fvip=1&keepalive=yes&fexp=23883098&c=WEB&txp=7316222&sparams=expire%2Cei%2Cip%2Cid%2Caitags%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRQIgYDqTm0CnLfG0kxsYNrAdtAUYB7alnowiaBArU8R5bBwCIQDeCRDJHFO_PWcnbeFaJvip80deuboN4Pi1x3eRhJBxlQ%3D%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRgIhAKTkyTIGVkbWWVx4lqFz77rOdG1FzkM5XuTnYOqtHT4oAiEA9u1R47jPz-mjj4DRXpqqqpUbfaFMW36KbG_pR2jovFM%3D&ratebypass=yes'
#Stores the result to a variable.
~ $ url_audio_part='https://r1---sn-3pm76n76.googlevideo.com/videoplayback?expire=1597593009&ei=UQE5X7bXEYqO4QLs17KACQ&ip=10.100.238.99&id=o-AD0HfadoeimIbuf9t8Anru5X9V7cER08YyOz4iKZOCHL&itag=251&source=youtube&requiressl=yes&mh=NV&mm=31%2C26&mn=sn-3pm76n76%2Csn-oguesnze&ms=au%2Conr&mv=m&mvi=1&pl=17&initcwndbps=908750&vprv=1&mime=audio%2Fwebm&gir=yes&clen=268945126&dur=17931.001&lmt=1597348111385641&mt=1597571322&fvip=1&keepalive=yes&fexp=23883098&c=WEB&txp=7311222&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&sig=AOq0QJ8wRgIhAK8XGu3vHucHwqERZ7TQniuvKEd-NTbMkwZbu8EXJ5E3AiEAiS7OYFOcsIrD2xp-AJNzucj1H9ZKMlmkCl_sU7__dZo%3D&lsparams=mh%2Cmm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=AG3C_xAwRgIhAKTkyTIGVkbWWVx4lqFz77rOdG1FzkM5XuTnYOqtHT4oAiEA9u1R47jPz-mjj4DRXpqqqpUbfaFMW36KbG_pR2jovFM%3D&ratebypass=yes'
#Downloads the video for one minute from 12:45.
~ $ ffmpeg -ss 12:45 -i "${url_video_part}" -ss 12:45 -i "${url_audio_part}" -t 1:00 output.mkv
frame= 3600 fps= 49 q=-1.0 Lsize= 27047kB time=00:00:59.99 bitrate=3692.9kbits/s speed=0.813x
这确实工作得很好。
对于一些视频†1 ，内部网址的形式为https://manifest.googlevideo.com/...，而不是https://RANDOM-STRING.googlevideo.com/...在上面的例子中为。
~ $ youtube-dl --get-url 'https://www.youtube.com/watch?v=KRMfnvLODZQ'
https://manifest.googlevideo.com/api/manifest/dash/expire/1597593866/ei/qgQ5X5maN8-ilQSu15W4CQ/ip/10.100.238.99/id/KRMfnvLODZQ.1/source/yt_live_broadcast/requiressl/yes/hfr/all/as/fmp4_audio_clear%2Cwebm_audio_clear%2Cwebm2_audio_clear%2Cfmp4_sd_hd_clear%2Cwebm2_sd_hd_clear/force_finished/1/vprv/1/keepalive/yes/fexp/23883098/itag/0/playlist_type/DVR/sparams/expire%2Cei%2Cip%2Cid%2Csource%2Crequiressl%2Chfr%2Cas%2Cforce_finished%2Cvprv%2Citag%2Cplaylist_type/sig/AOq0QJ8wRQIhANYKQvKTN8BRmhp7--4tQp9aqRp_qIGjh472BTYLyJ62AiAautFF86xGDHOe7mYlYaZ1W86EM4k2e6UiJS9Q91dMog%3D%3D
https://manifest.googlevideo.com/api/manifest/dash/expire/1597593866/ei/qgQ5X5maN8-ilQSu15W4CQ/ip/10.100.238.99/id/KRMfnvLODZQ.1/source/yt_live_broadcast/requiressl/yes/hfr/all/as/fmp4_audio_clear%2Cwebm_audio_clear%2Cwebm2_audio_clear%2Cfmp4_sd_hd_clear%2Cwebm2_sd_hd_clear/force_finished/1/vprv/1/keepalive/yes/fexp/23883098/itag/0/playlist_type/DVR/sparams/expire%2Cei%2Cip%2Cid%2Csource%2Crequiressl%2Chfr%2Cas%2Cforce_finished%2Cvprv%2Citag%2Cplaylist_type/sig/AOq0QJ8wRQIhANYKQvKTN8BRmhp7--4tQp9aqRp_qIGjh472BTYLyJ62AiAautFF86xGDHOe7mYlYaZ1W86EM4k2e6UiJS9Q91dMog%3D%3D
下载此类视频总是失败。
~ $ ffmpeg -ss 12:45 -i "${url_video_part}" -ss 12:45 -i "${url_audio_part}" -t 1:00 output.mkv
[dash @ 0x55fa6a1a4400] Manifest too large: 3776722
https://manifest.googlevideo.com/...: Invalid data found when processing input
请注意youtube-dl单独使用下载完整的此类视频会成功。
†1：就我们测试而言，最近（例如昨天）上传的视频具有此类 URL，当我们youtube-dl --get-url在一天左右后重试相同的命令时，我们会得到与第一个示例中类似的“无辜”URL。
如何下载此类视频的部分内容
通过为 指定附加选项ffmpeg，
通过以某种方式强制检索表单的内部 URL https://RANDOM-STRING.googlevideo.com/...，
或者我根本不知道的东西？
我目前的解决方法是等待一两天，直到内部 URL 发生变化，这比下载完整视频然后裁剪要慢得多。
~ $ lsb_release -d
Description: Arch Linux
~ $ ffmpeg -version
ffmpeg version n4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 10.1.0 (GCC)
configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-avisynth --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librav1e --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3
libavutil 56. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
libpostproc 55. 7.100 / 55. 7.100
~ $ youtube-dl --version
2020.07.28
有两种解决方法。
\n正如 OP 中所述，您只需等待几天，内部 URL 就会从\xe2\x80\xa01https://manifest.googlevideo.com/api/manifest/dash/...更改为https://r1---sn-3pm76n76.googlevideo.com/...。
据我测试，长视频（7-10 小时）至少需要一整天的时间。
\n通过以下步骤，您可以立即下载视频。
\nurl=\'https://www.youtube.com/watch?v=pkP-hgGJdvY\'（我选择此 URL 作为示例，因为在撰写此答案时youtube-dl --get-url "${url}"返回。）https://manifest.googlevideo.com/api/...
curl "${url}"
从 的输出中提取表单的curlURL 。请注意，此 URL 包含而不是.internal_urlhttps://manifest.googlevideo.com/api/manifest/hls_variant/.../hls_variant//dash/
ffmpeg -i "${internal_url}"有或没有任意选项来下载视频。
第 2 步和第 3 步的一行：
\ncurl --silent "${url}" | grep -o \'https:\\\\/\\\\/[^"]\\+googlevideo.com\\\\/[^"]\\+\' | grep \'hls_variant\' | sed \'s/\\\\//g\'\n即使通过上述方法，对于最近（例如几小时或一天前）直播结束的长（2小时以上）直播存档，也只能下载整个视频的最后2小时\xe2\x80\ xa02即使您可以在浏览器或官方应用程序上播放视频也没有问题。这个问题并不是特定的ffmpeg，实际上youtube-dlGitHub 存储库有一个相关问题：Youtube：仅下载 3 小时视频的最后 2 小时。（使用 hack 作为解决方法）#26330。（顺便说一下，这个问题的OP包含了这个问题的解决方法，由于我没有测试过，所以我不在这里写。）
考虑到\xe2\x80\xa01和\xe2\x80\xa02，问题似乎发生在目标视频的YouTube服务器端进程尚未完全完成时。虽然我根本不知道该怎么做，但也许应该有一些优雅的方法来克服最后两个小时的问题。
\n