Opened 3 years ago

#12728 new Bug Report - General

Mythtranscode reporting incorrect audio properties

Reported by: JP Briggs <jp.briggs@…> Owned by: JYA
Priority: minor Milestone: unknown
Component: MythTV - Mythtranscode Version: 0.27.6
Severity: medium Keywords: mythtranscode audio
Cc: Ticket locked: no

Description

I have a recording I am trying to transcode lossless to strip commercials. From there, I will re-encode using HandBrake?.

The original recording's audio is reported thusly (via mediainfo)

Audio #1
ID                                       : 6302 (0x189E)
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                                 : 35mn 58s
Bit rate mode                            : Constant
Bit rate                                 : 384 Kbps
Channel(s)                               : 6 channels
Channel positions                        : Front: L C R, Side: L R, LFE
Sampling rate                            : 48.0 KHz
Bit depth                                : 16 bits
Compression mode                         : Lossy
Delay relative to video                  : -562ms
Stream size                              : 98.8 MiB (2%)
Language                                 : English

I use mythtranscode from the CLI, and created the transcoded video thusly:

mythtranscode --chanid 1577 --starttime 20160327135900 --mpeg2 --honorcutlist -e ts --passthrough -o ~/tmp/myrecording.mpg

The audio of the resultant file (mediainfo):

Audio #1
ID                                       : 4301 (0x10CD)
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                                 : 24mn 29s
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                  : 8ms
Stream size                              : 33.6 MiB (1%)
Language                                 : English

Note the Channel(s) are reduced from 6 to 2, and the 'Bit rate' reduced to 192Bkps from 384Kbps.

This is, however, incorrect. Playing the transcoded file with VLC shows:

       Type: Audio
Original ID: 4301
      Codec: A52 Audio (aka AC3)(a52 )
   Language: Englisg
   Channels: 3F2R/LFE
Sample rate: 48000 Hz
    Bitrate: 384 kb/s

Note that it IS actually 6 channel, 384Kbps. So the audio of the file is correct, but the descriptors in the TS container are incorrect.

Unfortunately, when I open the transcoded file with HandBrake?, HandBrake? reports that the source audio is only 2 channel, and therefore cannot transcode to, e.g. AAC 6 channel; only 2.

Attachments (1)

mythtranscode_version.txt (965 bytes) - added by JP Briggs <jp.briggs@…> 3 years ago.
output of mythtranscode --version

Download all attachments as: .zip

Change History (1)

Changed 3 years ago by JP Briggs <jp.briggs@…>

Attachment: mythtranscode_version.txt added

output of mythtranscode --version

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