Digital TV MPEG-2 --> DivX

[dj_catalyst]

right, i'll try to keep this as short as possible... i've got a digital TV card that receives digital TV through an aerial (antenna on the roof). it can capture MPEG-2 at 720 x 576 (PAL) which is 16:9 anamorphic. sometimes it's interlaced and sometimes it's progressive depending on the channel...

so i can press record on the TV app and it captures away and after about half an hour, stop it, and it ends up with a massive mpeg file about a gig big!

play it back in media player and it recognises it's widescreen and corrects the aspect ratio... nice. all audio in sync and all video looking amazing...

but as soon as i try and edit it the sound jumps out of sync. here's a few things i've tried...

1) cut in TMPGEnc (MPEG Tools) to just the material i wanted... audio ends up a few seconds off. just re-checked it and it seems to be offset by the same amount all the way through...

2) convert to DivX by using DVD2AVI to make a .d2v file to use in GordianKnot, and an .mpa audio file (stripped out) to rename as .mp2 and disk-write in winamp to .wav to use in GordianKnot... this shows a delay of 550ms apparently... but when i try to correct with this or any other amount the audio will be perfectly in sync for a while then suddenly jump out of sync and stay that same amount offset until it jumps to another offset...

any ideas on this?

it's not going gradually out of sync... the audio and video seems to be at the same rate

i've converted loads of stuff before with all sorts of different offsets and rate differences including stuff captured from camcorder so i'm just a bit stuck with this...

can anyone help me out?

catalyst

[setarip]

What format, frequency, and sampling rate are you using for the audio capture?

[ivwshane]

With divx 5.02 I've been able to just leave the audio alone and select the .mpa file as the one to reencode with out any sync problems.

[dj_catalyst]

its 256kbps 48KHz mpeg1-layer2... the audio is not really captured as such... it's an audio stream mux'd in with the video as the whole digital TV mpeg-2 signal...

noticed another thing... it seems to jump out of sync when the frames become a little corrupted...

- playing back the original captured mpeg in any player doesn't show hardly any corruption... (the video might stutter for a very small fraction of a second)

- the encoded divx video shows a LOT of corruption - ghosting and smearing as well as blockiness / block errors...

it seems as though the problem is a drop of information in the video stream... still, it plays fine by itself... just the video won't encode in sync - so it seems the video frames get a different numbering...

i think i need to somehow get the encoding (whatever it may be) to keep the original frame-numbers...

soooooo, any ideas on this?

[setarip]

Use TMPGEnc to:

First, Demultiplex video and audio streams

Then, Multiplex video and audio streams

This may correct an interleaving problem.

(You might also try changing the audio frequency to 44,100Hz)

By the way, are you sure the audio sampling rate isn't at 224Kbps?

[vali]

yes, 10x

it really does the trick

thank you very much

[techno]

ur better of capturing straight to NO RECOMPRESSION YUY2/YU12 as it gives u a HIGH quality, sure, file size may be humungus but u can then convert it to DIVX fast motion 6000 bitrate or u can convert to MPEG2 using TMPGENC..

Techno

[dj_catalyst]

ok, before other people start goin off on one...

Originally posted by techno
ur better of capturing straight to NO RECOMPRESSION YUY2/YU12... (etc etc)

Techno

It's not a capture card... it's a digital TV card. The video is not captured because it's already encoded! It's 720 x 576, 25fps, PAL with 256kbps MPEG-1 Layer II audio...

ie. the standard Digital Video Broadcasting transmission (well, at least for that channel)

so it's not like i can choose a codec (or no codec) because it's just the received DVB multiplexed signal stream made into a file.

i haven't tried the de-multiplex then re-multiplex trick yet as i had to burn a buncha stuff to CD and then i got bored of the whole thing and also forgot to record one of the episodes of The Office... so i'll have to try it another time i reckon...

[dj_catalyst]

de-multiplex, multiplex

right, i tried doing a Simple De-Multiplex and then a Multiplex using MPEG-2 VBR (Program) settings in TMPGEnc Plus and it de-multiplexed fine...

but multiplexing the resulting m2v and mp2 files made an MPEG-2 mpg file that was slightly larger than the original (hmm, could maybe have filled in the missing/incomplete video frames maybe) but it also said that 12 s packet streams caused a overflow or something...

will keep trying... and let you know what happens