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I have to wrap an MPEG2 video file in an MXF container and convert the audio in the process. I have the MXF wrapping working but it won't convert the audio stream (which needs to be 16bit, 48kHz Linear PCM).

Here's what I'm trying:

ffmpeg -i input.mpg -map 0:0 -map 0:1 -vcodec copy -f mpeg2video -acodec pcm_s16le -ar 48000 -ac 2 output.mxf

Results:

ffmpeg version 0.10 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jan 30 2012 17:49:23 with gcc 4.2.1 (Apple Inc. build 5666) (dot 3)
  configuration: *{snipped}*
runtime-cpudetect
  libavutil      51. 34.101 / 51. 34.101
  libavcodec     53. 60.100 / 53. 60.100
  libavformat    53. 31.100 / 53. 31.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 60.100 /  2. 60.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0.  6.100 /  0.  6.100
  libpostproc    52.  0.100 / 52.  0.100
[mpeg @ 0x10201ae00] max_analyze_duration 5000000 reached at 5000000
Input #0, mpeg, from '/Volumes/Extra/test.mpg':
  Duration: 00:00:59.97, start: 0.192911, bitrate: 6513 kb/s
    Stream #0:0[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16, 384 kb/s
    Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x576 [SAR 16:15 DAR 4:3], 12000 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
Output #0, mpeg2video, to 'video.mxf':
  Metadata:
    encoder         : Lavf53.31.100
    Stream #0:0: Video: mpeg2video, yuv420p, 720x576 [SAR 16:15 DAR 4:3], q=2-31, 12000 kb/s, 25 fps, 90k tbn, 25 tbc
Stream mapping:
  Stream #0:1 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame= 1500 fps=  0 q=-1.0 Lsize=   43949kB time=00:00:59.96 bitrate=6004.6kbits/s    
video:43949kB audio:0kB global headers:0kB muxing overhead 0.000000%

The video plays fine as the MXF, but there is no audio stream at all. Any help would be great.

MFB
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2 Answers2

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In your command, video codec is specified as the output file format. As a result, the audio is stripped, and the output file is mpeg, not mxf.

The conversion can be done with the following command: 

ffmpeg -i input.mpg -vcodec mpeg2video -acodec pcm_s16le -ar 48000 -ac 2 output.mxf

The output file format will be guessed from the file extension. Alternatively, option -f mxf can be used. Due to MXF format limitations, frame rate may need to be specified -r 25. Options -vcodec and -acodec can be omitted to the same result.

Dmitry Shkuropatsky
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  • I know this is a late answer, but I had good results with `ffmpeg -i INPUT.mov -vcodec mpeg2video -qscale 1 -qmin 1 -ar 48000 OUTPUT.mxf` You can select a video quality level with -qscale:v n (or the alias -q:v n), where n=a number from 1-31, 1 being high-q/largest filesize & 31 being low-q/smallest filesize. This is a variable bit rate mode. [https://trac.ffmpeg.org/wiki/Encode/MPEG-4] qmax&qmin are the 'quality-ranges' to encode.qmin 50,qmax 51=low-q.qmin 0,qmax 1=high-q [https://stackoverflow.com/questions/18563764/why-low-qmax-value-improve-video-quality] – thvs86 Jan 14 '19 at 17:22
0

I think you're overspecifying things. Try:

ffmpeg -i input.mpg -vcodec copy -acodec pcm_s16le -ar 48000 -ac 2 output.mxf

You shouldn't need -map with simple input and output files having only one audio and one video stream. These days ffmpeg also knows how to format mxf files and can guess to use that format based on the extension.

I suspect that your problem was a result of specifying mpeg2video ('raw MPEG-2 video'), a format that doesn't appear to include audio.

blahdiblah
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  • Thanks blahdiblah but still no go. I tried your suggestion and then took it one step further `ffmpeg -i input.mpg output.mxf` and still no audio stream. Any other ideas? – MFB Feb 16 '12 at 03:08