[mythtv-users] MythTV 0.24-1.80 - No sound on HD TV recording

[John Pilkington]

On 25/04/12 14:33, PJR wrote:
>
>
> On 23/04/12 22:07, John Pilkington wrote:
>> On 23/04/12 19:51, PJR wrote:
>>> I recorded 'The Italian Job' from ITV HD the other day and when I play
>>> it there's sound from the TV broadcast prior to the movie but as soon as
>>> it starts there's no sound what so ever. This despite my AV amp
>>> (connected to the mythbox by HDMI) showing it's receiving 5.1 sound but
>>> no sound out of the speakers.  All other HD TV recordings playback sound
>>> in the appropriate number of channels.  Any thoughts as to what's gone
>>> wrong?   Setting or un-setting Dolby, DTS etc in mythfrontend makes no
>>> difference. The TV decoder is a PC nano Stick 290e which has worked
>>> without fault.
>>
>> vlc hung up when asked to play my recording but was fine after I
>> chopped off the beginning.  There isn't any sound anyway until the
>> initial pan down gets to the viaduct.
>>
>> ffmpeg -i on the chopped file says:
>>      Stream #0:0[0x12d]: Video: h264 (High) ([27][0][0][0] / 0x001B),
>> yuv420p, 1440x1080 [SAR 4:3 DAR 16:9], 29.17 fps, 50 tbr, 90k tbn, 50 tbc
>>      Stream #0:1[0x12e](eng): Audio: aac_latm ([17][0][0][0] / 0x0011),
>> 48000 Hz, 5.1, s16
>>      Stream #0:2[0x132](eng): Audio: aac_latm ([17][0][0][0] / 0x0011),
>> 48000 Hz, 2 channels (FC), s16 (visual impaired)
>>      Stream #0:3[0x131](eng): Subtitle: dvb_subtitle ([6][0][0][0] /
>> 0x0006)
>>

> What did you use to chop off the beginning of the file?  I don't want to
> upgrade to 0.25 just yet; there seems a lot of issues with it and it's
> taken me some time to get 0.24 working on my h/w setup.  Is there a
> backport of the AAC audio updates to 0.24 or some such?

I think the usual way of chopping bits out of a video is to use dd; 
something like this:

dd if=/path/to/original.mpg of=sample.mpg bs=1M count=100

You can adjust --skip and --count to locate the bits you want.  I'm 
playing with a keyframe-linked cutter similar to mythcutprojectx that 
should work with HD and a myth cutlist but it still needs more tlc.

I don't use HD often but I haven't noticed this problem in 0.24.3.  OTOH 
I would have recorded with 0.25 and then rsynced to 0.24, so maybe the 
difficult bits had already been cut.