[libav-tools] Problem with ac3 audio

Bernard Giannetti thebernmeister at hotmail.com
Wed May 20 01:24:35 CEST 2015


Hi,
I am using avconv to cut sections out of recordings from Mythbuntu 12.04.  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, the original recording (and trimmed recording) have audio mp2.  When I get a 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 I took the recordings to my Ubuntu 14.04 to try there and have the same issue (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 files play fine using the Mythbuntu playback - video and audio is present, regardless of audio mp2 or ac3.  However, of those original recordings, those which are mp2 will play in VLC, but not those recordings which are ac3 (audio is missing).
Am I missing a codec for ac3?  I checked what packages I have 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 with missing 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 the audio 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 both audio 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 also video resolution differences, but same codec.

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

Thanks in advance,Bernard. 		 	   		   		 	   		  
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