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• ffmpeg Produces unplayable MP4 File From avi files

  25 août 2021, par Manngo

  A have a hand full of .avi files which I would like to convert to .mp4. Cobbling together everything I have found on the Internet, I end up with something like this :

  


  ffmpeg -i something.avi -c:v copy -c:a copy something.mp4


  


  What I get is playable on VLC player, but, of course, that will play anything I through at it. However, I cannot play it using QuickLook in the Finder or with the QuickTime player.

  


  In some cases I get video, but no sound. In some other cases I get garbled video.

  


  I am guessing that the audio or video codec inside the .avi file is incompatible with MacOS, and that the copy instruction above is not appropriate. In that case I guess that I would actually need to reencode the audio or video.

  


  If this sounds incoherent, I admit I know very little about video files.

  


  What would be the best settings to try to produce an MP4 which works natively on MacOS ?

  


• Download multiple files with ffmpeg, keep one stream from each (according to default stream selection), and then mux them into single file ?

  23 août 2021, par Bernard

  With ffmpeg, I can download m3u8 streams with the following command :

  


  ffmpeg -i http://example.com/test.m3u8 -c copy output.mp4


  


  The above command will keep the best quality video and audio (to some definition of 'best').

  


  However, I'm faced with a situation where I have several m3u8 streams, all of them possibly containing zero or more video or audio streams. I would like to take at most one video and audio from each url (according to ffmpeg's definition of 'best'), and mux them together into the final mp4 file.

  


  This is essentially what I want :

  


  ffmpeg -i http://example.com/test0.m3u8 -c copy output0.mp4
ffmpeg -i http://example.com/test1.m3u8 -c copy output1.mp4
ffmpeg -i http://example.com/test2.m3u8 -c copy output2.mp4
ffmpeg -i output0.mp4 -i output1.mp4 -i output2.mp4 -map 0 -map 1 -map 2 -c copy output.mp4


  


  Is there any way to do it without the temporary files ?

  


• ffmeg : audio drifts in merged TS file for separate audio and video TS files

  13 septembre 2021, par Ronnie Marksch

  basic situation

  


  I have two lists of TS files (each list is specified in an m3u8 file).
The TS files in the first list have only video.
The TS files in the second list have only audio.

  


  I combine the TS files from the first list to get the video only file result_video.ts of duration A (see code for this used below).
I combine the TS files from the second list to get the audio only file result_audio.ts of duration B (see code for this used below).
The problem is that A * 76.28% = B whereas I expected both files to have the same length.
I then combine result_video.ts and result_audio.ts and get a result.ts file where the audio drifts from the video heavily and where the audio has gaps at the points where the chunks have been merged.

  


  Question : how to ensure that the audio is not too slow ? or : how to combine the TS files properly.

  


  code for obtaining the two result files

  


  ffmpeg -safe 0 -f concat -i filelist_video.txt -c copy result_video.ts
ffmpeg -safe 0 -f concat -i filelist_audio.txt -c copy result_audio.ts


  


  code for obtaining the final result

  


  ffmpeg.exe -i .\video_merge_0.ts -i .\audio_merge_0.ts -c copy result.ts


  


  test using only one TS file

  


  I copied the first of the audio input TS files to another TS file.
Doing that produced the output below with a muxing overhead of 22.44%, which is suspiciously close to 1-76.28%.

  


  ffmpeg.exe -i audio_chunk1.ts -c copy audio_chunk1_tmp.ts


  


  I get the info :

  


  Output #0, mpegts, to 'audio_chunk1.ts':
  Metadata:
    encoder         : Lavf58.45.100
    Stream #0:0: Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 125 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
size=     118kB time=00:00:05.99 bitrate= 161.1kbits/s speed=3.48e+03x
video:0kB audio:96kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 22.444508%


  


  using hls

  


  The following now produces files audio_chunk1_tmp.ts, audio_chunk1_tmp0.ts, ... audio_chunk1_tmp2.ts. So for some reason, the single file already gets split. However, ffmpeg shows that the duration of the result is 5.99s for the 5.87s input (which may be ok).

  


  ffmpeg.exe -i audio_chunk1.ts -f hls audio_chunk1_tmp.ts