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• What format/protocol does ffmpeg use for "raw" output ?

  9 janvier 2021, par MSalters

  Given a commandline ffmpeg -f lavfi -i "sine=frequency=1000:duration=5" -ar 8000 -c:a FOO pipe:1, ffmpeg might complain it's "unable to find a suitable output format". For some codecs, ffmpeg has a default container format, e.g. -c:a libmp3lame will produce MP3's. For other codecs, you just repeat yourself (sort of) : -c:a pcm_alaw -f alaw

  



  But what if I want to stream the raw codec output, and there's no matching -f ? Can I just take -f alaw and assume that it doesn't do anything ? (G711 alaw is a simple codec which produces a byte stream, so -f alaw presumably just copies that byte stream)

  



  Obviously the other side of the pipe needs to know how the data stream needs to be interpreted, if there's no container info. But assume that I already know the other side of the pipe is expecting an audio stream, sampled at 8 kHz, encoded with -c:a FOO.

  


• Strange "pause" in video after concatenation of two mp4 videos

  23 janvier 2021, par user606521

  I am concatenating two mp4 videos. The problem is that first video (intro.mp4) lasts 5 seconds, second video (output.mp4) lasts 2 seconds and video created by concatenating them lasts 9 seconds (and should last 5+2 = 7 seconds). In final.mp4 video the last frame from first video (intro.mp4) i shown for additional 2 seconds before second video (output.mp4) is played. It looks like a lag when watching video. What I am doing wrong ?

  



  list.txt :

  



  file 'data/intro.mp4'
file 'output.mp4'


  



  command :

  



  ./bin/ffmpeg -f concat -i list.txt -c copy final.mp4


  



  output :

  



  ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
  configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc --arch=x86_64 --enable-runtime-cpudetect
  libavutil      54. 27.100 / 54. 27.100
  libavcodec     56. 41.100 / 56. 41.100
  libavformat    56. 36.100 / 56. 36.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 16.101 /  5. 16.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a6a80e600] Auto-inserting h264_mp4toannexb bitstream filter
Input #0, concat, from 'list.txt':
  Duration: N/A, start: 0.000000, bitrate: 1296 kb/s
    Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p, 960x540, 1163 kb/s, 23.98 fps, 23.98 tbr, 11988 tbn, 47.95 tbc
    Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 133 kb/s
[mp4 @ 0x7f8a6c006a00] Codec for stream 0 does not use global headers but container format requires global headers
[mp4 @ 0x7f8a6c006a00] Codec for stream 1 does not use global headers but container format requires global headers
Output #0, mp4, to 'final.mp4':
  Metadata:
    encoder         : Lavf56.36.100
    Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 960x540, q=2-31, 1163 kb/s, 23.98 fps, 23.98 tbr, 11988 tbn, 11988 tbc
    Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, stereo, 133 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a6a80e600] Auto-inserting h264_mp4toannexb bitstream filter
frame=  258 fps=0.0 q=-1.0 Lsize=     997kB time=00:00:09.84 bitrate= 829.5kbits/s    
video:897kB audio:93kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.634306%


  


• How to decrypt AES 128 encrypted HLS stream when URI for key is "k/timestamp"

  25 janvier 2021, par Wilfred Almeida

  I have downloaded 1784 .ts files and they are AES 128 encrypted.

  


  The .m3u8 file has #EXT-X-KEY:METHOD=AES-128,URI="k/timestamp",IV=0x496daa1c6914000e408c65cead91fc29 which I guess indicates that the key must be in a file named timestamp. I got the "timestamp" file and now I want to decrypt.

  


  I tried replacing the URI with URI="file:timestamp" with all the .ts, the .m3u8 and the timestamp file all in same directory and ran the ffmpeg command

  


  ffmpeg -allowed_extensions ALL -protocol_whitelist file,tcp,crypto,http,https  -i playlist.m3u8 -c copy op.mp4

  


  but got the errors Error when loading first segment 'hls_350k_000.ts'                                  playlist.m3u8: Invalid data found when processing input even though it opened the file successfully.

  


  I tried specifying the URI as URI="http://localhost/mydir/timestamp" but got the same error as specified above. I had all .ts,.m3u8,"timestamp" file in XAMPP's htdocs folder.

  


  When I open the "timestamp" file in browser's inspect->Network->Click on file->preview, I see weird text like kf¯2“.ú¸“Á•ª   Bn5ydr/x$.9+cgKC!<ßû¢ÌNñ®jûŸŸ and it changes everytime I refresh the site.

  


  I specified the link of the file in URI and tried, same error.

  


  I tried specifying .key extension to the "timestamp" file, same error.

  


  I downloaded the "timestamp" file by entering its URL into browser which I got from inspect->Network->Click on file->Headers, I didn't download it as HAR or other stuff.

  


  I tried playing the .m3u8 file in chrome using chrome by using Native HLS Playback extension with files hosted using XAMPP but it doesn't play, video player shows loading and the chrome's console has following errors

  


  (anonymous) @ player.js:57
player.js:11 trying to recover from media Error ...
handleMediaError @ player.js:11
hls.0.12.4.min.js:1 Uncaught (in promise) DOMException: The play() request was interrupted by a new load request.
player.js:57 Player error: mediaError - fragParsingError
(anonymous) @ player.js:57
player.js:17 trying to swap Audio Codec and recover from media Error ...
handleMediaError @ player.js:17
player.js:57 Player error: mediaError - fragParsingError
(anonymous) @ player.js:57
player.js:22 cannot recover, last media error recovery failed ...
handleMediaError @ player.js:22
DevTools failed to load SourceMap: Could not load content for chrome-extension://emnphkkblegpebimobpbekeedfgemhof/hlsjs/hls.min.js.map: HTTP error: status code 404, net::ERR_UNKNOWN_URL_SCHEME


  


  I tried combining the .ts files using ffmpeg but got the same errors specified above.

  


  How do I decrypt the files and combine them into a single vlc playable file ?