[libav-tools] Problem with ac3 audio

Bernard Giannetti thebernmeister at hotmail.com
Wed May 20 01:31:44 CEST 2015


(second post to break at 70 characters)
Hi,
I am using avconv to cut sections out of recordings from Mythbuntu12.04.  With some, I get the desired portion of the original recording and I can play in VLC.  With others, I get the video but no audio.
Using avprobe, I noticed that when I get both video/audio, theoriginal recording (and trimmed recording) have audio mp2.  When I geta trimmed recording which is missing the audio, the original recording(and trimmed recording) has audio ac3.

Mythbuntu 12.04 uses avconv 0.8.17-4:0.8.17-0ubuntu0.12.04.1, so Itook the recordings to my Ubuntu 14.04 to try there and have the sameissue (Ubuntu 14.04 uses avconv version 9.18-6:9.18-0ubuntu0.14.04.1).

If I play the original recordings (as recorded by Mythbuntu) all filesplay fine using the Mythbuntu playback - video and audio is present,regardless of audio mp2 or ac3.  However, of those originalrecordings, those which are mp2 will play in VLC, but not thoserecordings which are ac3 (audio is missing).
Am I missing a codec for ac3?  I checked what packages are installed:
dpkg -s libavcodec-extra-53 | grep StatusStatus: deinstall ok config-files
dpkg -s libavcodec-dev | grep StatusPackage `libavcodec-dev' is not installed and no info is available.
dpkg -s libavcodec53 | grep StatusStatus: install ok installed

I installed libavcodec-extra-53 and that did not help.
The avconv command and output for the recording which ends up withmissing audio is below:
$ avconv -i inputFile.mpg -ss 00:12:00 -t 0:03:00 -codec copy outputFile.mpgavconv version 0.8.17-4:0.8.17-0ubuntu0.12.04.1, Copyright (c) 2000-2014 the Libav developers    built on Mar 16 2015 13:26:50 with gcc 4.6.3[mpegts @ 0xa797a0] Continuity check failed for pid 0 expected 10 got 11[mpegts @ 0xa797a0] max_analyze_duration reached[NULL @ 0xa9d1e0] start time is not set in estimate_timings_from_pts[NULL @ 0xa9f200] start time is not set in estimate_timings_from_pts[NULL @ 0xaa1220] start time is not set in estimate_timings_from_pts[NULL @ 0xaa3280] start time is not set in estimate_timings_from_ptsInput #0, mpegts, from 'inputFile.mpg':  Duration: 02:55:00.32, start: 67038.441011, bitrate: 8362 kb/s  Program 1     Stream #0.0[0x200]: Video: mpeg2video (Main), yuv420p, 1440x1080 [PAR 4:3 DAR 16:9], 80000 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc    Stream #0.1[0x28a](eng): Audio: ac3, 48000 Hz, 5.1, s16, 448 kb/s    Stream #0.2[0x240](eng): Subtitle: [6][0][0][0] / 0x0006    Stream #0.3[0x901]: Data: [11][0][0][0] / 0x000B    Stream #0.4[0x321]: Data: [5][0][0][0] / 0x0005    Stream #0.5[0x322]: Data: [11][0][0][0] / 0x000B    Stream #0.6[0x323]: Data: [12][0][0][0] / 0x000COutput #0, mpeg, to 'outputFile.mpg':  Metadata:    encoder         : Lavf53.21.1    Stream #0.0: Video: mpeg2video, yuv420p, 1440x1080 [PAR 4:3 DAR 16:9], q=2-31, 80000 kb/s, 90k tbn, 90k tbc    Stream #0.1(eng): Audio: ac3, 48000 Hz, 5.1, 448 kb/sStream mapping:  Stream #0:0 -> #0:0 (copy)  Stream #0:1 -> #0:1 (copy)Press ctrl-c to stop encoding[mpegts @ 0xa797a0] Continuity check failed for pid 0 expected 10 got 11Continuity check failed for pid 576 expected 13 got 1200000.00 bitrate=   0.0kbits/s    [mpegts @ 0xa797a0] Continuity check failed for pid 512 expected 0 got 9[mpegts @ 0xa797a0] Continuity check failed for pid 2305 expected 15 got 7[mpegts @ 0xa797a0] Continuity check failed for pid 802 expected 9 got 1[mpegts @ 0xa797a0] Continuity check failed for pid 803 expected 5 got 11[mpegts @ 0xa797a0] PES packet size mismatch[mpegts @ 0xa797a0] Continuity check failed for pid 801 expected 13 got 0frame= 4495 fps=1973 q=-1.0 Lsize=  188808kB time=179.96 bitrate=8594.8kbits/s    /s    video:178165kB audio:9844kB global headers:0kB muxing overhead 0.424872%

The avprobe output for the recording which ultimately is missing theaudio is:
$ avprobe fileAC3.mpgavprobe version 0.8.17-4:0.8.17-0ubuntu0.12.04.1, Copyright (c) 2007-2014 the Libav developers  built on Mar 16 2015 13:26:50 with gcc 4.6.3[mpegts @ 0x13c77a0] Continuity check failed for pid 0 expected 10 got 11[mpegts @ 0x13c77a0] max_analyze_duration reached[NULL @ 0x13eb180] start time is not set in estimate_timings_from_pts[NULL @ 0x13ed1a0] start time is not set in estimate_timings_from_pts[NULL @ 0x13ef1c0] start time is not set in estimate_timings_from_pts[NULL @ 0x13f1220] start time is not set in estimate_timings_from_ptsInput #0, mpegts, from '../Recordings/1090_20150508131000.mpg':  Duration: 02:55:00.32, start: 67038.441011, bitrate: 8362 kb/s  Program 1     Stream #0.0[0x200]: Video: mpeg2video (Main), yuv420p, 1440x1080 [PAR 4:3 DAR 16:9], 80000 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc    Stream #0.1[0x28a](eng): Audio: ac3, 48000 Hz, 5.1, s16, 448 kb/s    Stream #0.2[0x240](eng): Subtitle: [6][0][0][0] / 0x0006    Stream #0.3[0x901]: Data: [11][0][0][0] / 0x000B    Stream #0.4[0x321]: Data: [5][0][0][0] / 0x0005    Stream #0.5[0x322]: Data: [11][0][0][0] / 0x000B    Stream #0.6[0x323]: Data: [12][0][0][0] / 0x000CUnsupported codec with id 94215 for input stream 2Unsupported codec with id 0 for input stream 3Unsupported codec with id 0 for input stream 4Unsupported codec with id 0 for input stream 5Unsupported codec with id 0 for input stream 6

The avprobe output for the recording which ultimately contains bothaudio and video is:
$ avprobe ../Recordings/1099_20150518092500.mpgavprobe version 0.8.17-4:0.8.17-0ubuntu0.12.04.1, Copyright (c) 2007-2014 the Libav developers  built on Mar 16 2015 13:26:50 with gcc 4.6.3[mpegts @ 0x21847a0] Continuity check failed for pid 0 expected 4 got 6[mpegts @ 0x21847a0] max_analyze_duration reached[NULL @ 0x21a8180] start time is not set in estimate_timings_from_pts[NULL @ 0x21aa1a0] start time is not set in estimate_timings_from_pts[NULL @ 0x21ac1c0] start time is not set in estimate_timings_from_pts[NULL @ 0x21ae220] start time is not set in estimate_timings_from_ptsInput #0, mpegts, from '../Recordings/1099_20150518092500.mpg':  Duration: 01:04:59.24, start: 58562.148622, bitrate: 3442 kb/s  Program 1     Stream #0.0[0x205]: Video: mpeg2video (Main), yuv420p, 720x576 [PAR 64:45 DAR 16:9], 15000 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc    Stream #0.1[0x2bc](eng): Audio: mp2, 48000 Hz, stereo, s16, 192 kb/s    Stream #0.2[0x245](eng): Subtitle: [6][0][0][0] / 0x0006    Stream #0.3[0x901]: Data: [11][0][0][0] / 0x000B    Stream #0.4[0x321]: Data: [5][0][0][0] / 0x0005    Stream #0.5[0x322]: Data: [11][0][0][0] / 0x000B    Stream #0.6[0x323]: Data: [12][0][0][0] / 0x000CUnsupported codec with id 94215 for input stream 2Unsupported codec with id 0 for input stream 3Unsupported codec with id 0 for input stream 4Unsupported codec with id 0 for input stream 5Unsupported codec with id 0 for input stream 6

Aside from audio differences between the two files, there are alsovideo resolution differences, but same codec.

Any ideas on why the AC3 audio does not come through to the outputfile please?

Thanks in advance,
Bernard. 		 	   		   		 	   		   		 	   		  
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