[mythtv-users] Mythexport choosing wrong audio stream

[John Pilkington]

On 03/12/12 23:01, Stephen Robertson wrote:
> On Mon, Dec 3, 2012 at 5:40 PM, Karl Dietz
> <dekarl at spaetfruehstuecken.org> wrote:
>> On 03.12.2012 18:21, Stephen Robertson wrote:
>>>
>>> It seems that for some recordings the resultant video from mythexport
>>> has the "wrong" audio track.  In my case I get an audio description
>>> track.  I think this may be the first audio track and the normal audio
>>> is on the second.  Is there a way tell mythexport which stream to use.
>>
>>
>> Which version is that? (of MythTV and MythExport)
>> Where do you source the recording from? (DVB-C/S/T of which country)
>>
>> Regards,
>> Karl
>
> Sorry for the vague information earlier
>
> Mythexport  2.2.4-0ubuntu1
>
> MythTV Version : v0.26.0-51-ged7b577
> MythTV Branch : fixes/0.26
> Network Protocol : 75
> Library API : 0.26.20120822-1
> QT Version : 4.8.1
>
> I've seent this in
> BBC HD from DVB-S2 in the UK
>
> ffmpeg line from mythxport config:
>   system("avconv -i \'$self->{_inputFile}\' -y -pass 1 -an -vcodec
> libx264 -pre:v libx264-medium_firstpass -pre:v libx264-ipod640 -b
> 1500k -bt 1000k -threads 0 -s 800x480 -aspect 16:9 -f ipod '/dev/null'
> && avconv -i \'$self->{_inputFile}\' -y -pass 2 -vcodec libx264
> -preset medium -pre:v libx264-ipod640 -b 1500k -bt 1000k -threads 0 -s
> 800x480 -acodec libfaac -ab 192k -ar 48000 -ac 2 -aspect 16:9 -f ipod
> \'$self->{_outputFile}$self->{_extension}\'")
>
>
> mediainfo otuput for a recording that exhibited this:
> General
> ID                                       : 2050 (0x802)
> Complete name                            :
> /media/disk/Recordings/8940_20121013202800.mpg
> Format                                   : MPEG-TS
> File size                                : 2.58 GiB
> Duration                                 : 31mn 57s
> Overall bit rate                         : 11.5 Mbps
>
> Video
> ID                                       : 5500 (0x157C)
> Menu ID                                  : 1 (0x1)
> Format                                   : AVC
> Format/Info                              : Advanced Video Codec
> Format profile                           : High at L4.0
> Format settings, CABAC                   : Yes
> Format settings, ReFrames                : 4 frames
> Codec ID                                 : 27
> Duration                                 : 31mn 56s
> Bit rate                                 : 10.5 Mbps
> Width                                    : 1 920 pixels
> Height                                   : 1 080 pixels
> Display aspect ratio                     : 16:9
> Frame rate                               : 25.000 fps
> Color space                              : YUV
> Chroma subsampling                       : 4:2:0
> Bit depth                                : 8 bits
> Scan type                                : MBAFF
> Bits/(Pixel*Frame)                       : 0.203
> Stream size                              : 2.35 GiB (91%)
> Color primaries                          : BT.709
> Transfer characteristics                 : BT.709
> Matrix coefficients                      : BT.709
>
> Audio #1
> ID                                       : 5501 (0x157D)
> Menu ID                                  : 1 (0x1)
> Format                                   : AC-3
> Format/Info                              : Audio Coding 3
> Mode extension                           : CM (complete main)
> Format settings, Endianness              : Big
> Codec ID                                 : 129
> Duration                                 : 31mn 57s
> Bit rate mode                            : Constant
> Bit rate                                 : 192 Kbps
> Channel(s)                               : 2 channels
> Channel positions                        : Front: L R
> Sampling rate                            : 48.0 KHz
> Bit depth                                : 16 bits
> Compression mode                         : Lossy
> Delay relative to video                  : -853ms
> Stream size                              : 43.9 MiB (2%)
> Language                                 : English
>
> Audio #2
> ID                                       : 5502 (0x157E)
> Menu ID                                  : 1 (0x1)
> Format                                   : MPEG Audio
> Format version                           : Version 1
> Format profile                           : Layer 2
> Codec ID                                 : 3
> Duration                                 : 31mn 57s
> Bit rate mode                            : Constant
> Bit rate                                 : 256 Kbps
> Channel(s)                               : 2 channels
> Sampling rate                            : 48.0 KHz
> Compression mode                         : Lossy
> Delay relative to video                  : -858ms
> Stream size                              : 58.5 MiB (2%)
> Language                                 : nar
>
> Text #1
> ID                                       : 5503 (0x157F)-888
> Menu ID                                  : 1 (0x1)
> Format                                   : Teletext Subtitle
> Language                                 : English
>
> Text #2
> ID                                       : 5504 (0x1580)
> Menu ID                                  : 1 (0x1)
> Format                                   : DVB Subtitle
> Codec ID                                 : 6
> Duration                                 : 31mn 55s
> Delay relative to video                  : 2s 378ms
> Language                                 : English


mediainfo shows that you would want Audio #2 for this recording, but the 
script is using avconv -i for analysis.  Does that give the same order? 
  Can you switch channels on playback?  The -ac 2 suggests (to me) that 
both channels would be passed.

John P