[mythtv-users] Problems with audio in DVB transcodes

[Kent Williams]

Sorry it has taken me so long to reply!
I've managed to get recordings from other channels to transcode correctly, however none from this particular station (ABC in NSW, AU) despite the recordings from this station playing back fine on the frontend.

Has anyone around Sydney had any luck transcoding a show from ABC?
Any other ideas? I've got about 100gb or a particular series that I really need to compress before I run out of space :)

Cheers,
Kent


-----Original Message-----
From: Kenneth Aafløy [mailto:ke-aa at frisurf.no] 
Sent: Sunday, 25 January 2004 3:37 PM
To: 'Discussion about mythtv'
Subject: RE: [mythtv-users] Problems with audio in DVB transcodes

Kent Williams wrote:
> I can't seem to get the audio in my DVB transcodes to work properly.
> I've tried many different settings for the MPEG2 profile under
> transcoders but each gives the same results. For the 'MP3' codec I've
> tried sampling rates of 32kHz, 44.1kHz, and 48kHz. One interesting
> point is that when changing the codec to 'uncompressed' (only tried
> this with a sample rate of 48kHz) I still get the same problem. This
> suggests to me that the problem is in the decoding?
> 
> I've created a short 30 second clip that can probably explain things
> better: http://scuznet.dyndns.org:8888/files/6005_20040121060000_20040

I have essentially no clue as where this problem might come from,
however, I can confirm that DVB transcoding works as a charm (from my
point of view), as I've used it' on a show for a couple of months now.

> The following is what is shown on mythbackend:
> Input #0, mpeg, from
> '/mnt/massstore/recordings/6005_20040121060000_20040121063000.nuv':
>  Stream #0.0: Video: mpeg2video, 720x576, 25.00 fps
>  Stream #0.1: Audio: mp2, 48000 Hz, stereo, 256 kb/s
> 2004-01-25 14:58:53 Fast-Forwarding from 0 to 5989
> 2004-01-25 14:59:23 Fast-Forwarding from 6739 to 53331
> [mpeg2video @ 0x84290c8]invalid mb type in P Frame at 35 2
> [mpeg2video @ 0x84290c8]concealing errors
> [mpeg2video @ 0x84290c8]Warning MVs not available
> 2004-01-25 14:59:25 Transcoding
> /mnt/massstore/recordings/6005_20040121060000_20040121063000.nuv done
>
> Any help would be very much appreciated!

What I want to point out, is that you probably have an on egde signal
issue (ie, your antenna is off a bit), or there has been some very
bad wether when you recorded this show. The invalid mb (macroblock)
won't come from a providers encoded mpeg2.

What follows is that the transcoder might be confused about the
errors in the stream, and misinterpret it's information.

Could you confirm this error with a recording that does not
excibit this kind of errors in it?

Kenneth

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