[mythtv-commits] Ticket #12303: transcoding to Nuppelvideo loses audio

MythTV noreply at mythtv.org
Thu Feb 26 17:24:45 UTC 2015


#12303: transcoding to Nuppelvideo loses audio
------------------------------------+--------------------------------
 Reporter:  ssd.mtv@…               |          Owner:  jyavenard
     Type:  Bug Report - General    |         Status:  infoneeded_new
 Priority:  major                   |      Milestone:  unknown
Component:  MythTV - Mythtranscode  |        Version:  0.27-fixes
 Severity:  medium                  |     Resolution:
 Keywords:  transcode audio         |  Ticket locked:  0
------------------------------------+--------------------------------

Comment (by Nicolas Pöhlmann <nicolas.poehlmann@…>):

 Replying to [comment:23 dekarl]:
 it seems to be an error when transcoding 5.1 audio channels to mp3-format,
 at least wrong frame size is selected for audio.

 before [cut down to necessary information]:
 ffprobe version 1.2.7 Copyright (c) 2007-2014 the FFmpeg developers
 ...
 Input #0, mpegts, from
 '/media/MythTV_Disk2/MythTV/Standard/13120_20150221191000.mpg':
   Duration: 01:04:58.66, start: 90506.666933, bitrate: 6079 kb/s
     Stream #0:0[0x1a05]: Video: h264 (High), yuv420p, 1280x720 [SAR 1:1
 DAR 16:9], 50 fps, 50 tbr, 90k tbn, 100 tbc
     Stream #0:1[0x1a06](deu): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448
 kb/s
     Stream #0:2[0x1a07](fra): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
     Stream #0:3[0x1a08](ger): Subtitle: dvb_teletext
     Stream #0:4[0x1a09](deu): Subtitle: dvb_subtitle
     Stream #0:5[0x1a0a](fra): Subtitle: dvb_subtitle
 Unsupported codec with id 94215 for input stream 3
 [dvbsub @ 0x1aae8c0] Invalid extradata, subtitle streams may be combined!
 [dvbsub @ 0x1aaf440] Invalid extradata, subtitle streams may be combined!

 after [cut down to necessary information]:
 ffprobe version 1.2.7 Copyright (c) 2007-2014 the FFmpeg developers
 ...
 [nuv @ 0x1febea0] max_analyze_duration 5000000 reached at 5000000
 microseconds
 [nuv @ 0x1febea0] Could not find codec parameters for stream 1 (Audio: mp3
 (LAME / 0x454D414C), 48000 Hz, 2 channels, s16p, 1411 kb/s): unspecified
 frame size
 Consider increasing the value for the 'analyzeduration' and 'probesize'
 options
 [nuv @ 0x1febea0] Estimating duration from bitrate, this may be inaccurate
 Input #0, nuv, from
 '/media/MythTV_Disk2/MythTV/Standard/13120_20150221191000.nuv':
   Duration: 04:50:57.46, start: 0.020000, bitrate: 1411 kb/s
     Stream #0:0: Video: mpeg4 (DIVX / 0x58564944), yuv420p, 1280x720, SAR
 1:1 DAR 16:9, 50 fps, 50 tbr, 1k tbn, 1k tbc
     Stream #0:1: Audio: mp3 (LAME / 0x454D414C), 48000 Hz, 2 channels,
 s16p, 1411 kb/s

 But this time it's NOT a similar problem like in #11639. it only affects
 5.1/x.1 channel transcoding. stereo recordings are NOT affected.

 PROBLEM:
 The AudioReencodeBuffer frames in the transcode.cpp file [Line 286 and
 1338] aren't filled, so that no audio frames at all can be even processed.
 I assume that there must be a problem filling them while trying to down
 5.1 channels to 2.

 As I'm not an audio/lame expert, maybe another one can take a look into
 that problem.

 Better solution would be if there is someone out which can implement an
 option for the mp3-surround extension:
 http://en.wikipedia.org/wiki/MP3_Surround

--
Ticket URL: <https://code.mythtv.org/trac/ticket/12303#comment:24>
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