I have some AVI files with AC3 audio, in order to mantain that audio I do this :
Demux audio AC3 with VirtualDubMod
convert audio AC3 23.976 FPS to 25 FPS for DVD-PAL compatibility, with BesWeet
But the resulting DVD is a audio out of sync
here is the scripts I use :
1) demuxing audio :
2) converting to 25 FPS for a DVD-PAL output :
besweet.exe -core( -input "audio.ac3" -output "audio_fix.ac3" ) -ota( -r 23976 25000 ) -ssrc( --rate 48000 ) -azid( -g max -c normal ) -ac3enc( -b 384 -6ch )
3) muxing :
mplex.exe -f 8 -o "multiplex.mpg" "movie.mpv" "audio_fix.ac3"
Resulting DVD :
Audio is out of sync
what can I do in order to use original AC3 audio from sources but without sync problems ?
thanks for any help
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Couple of suggestions is
- don't change the audio. And encode the video originally at 23.976 but with PAL res 720x576. Then import video into dgpulldown and customize pulldown - 23.976 --> 25.
- (What I would do) encode your video by speeding up the video to 25fps. If you use avisynth use the function at the end of the script - assumefps(25)
doesn't do the same ?
I need to make a DVD-PAL 25 FPS
I will try some of your suggestions
all NTSC sources result in a bad PAL
Besweet sped up your audio. Compare the running times of the original ntsc-ac3 and the pal-ac3. You will see the pal one is shorter. AFAIK convertfps doesn't speed up or slow down the video when encoding. I think it does some blending. So that's why the audio is out of sync. Assumefps does change the final running time of the video so that it will match your converted audio from besweet.
When using assumfps make sure it has its own line. Don't put it with your source file line:
if you are going to use AC3 from a avi file always run it through ac3fix.exe first before you use the file. also whenever i use besweet for ac3's i get crackles and pops on some ac3's. so now what i do is jut convert to 2 channel stero wave with besweet, then use Vegas to encode to 2 channel ac3. if you dont have vegas you can use ffmpeggui03 which is good but not as good as vegas.
Thanks guys, I think I have solved that problem with AssumeFPS
But I have another question :
The audio bitrates
A audio with 121 kbps (low bitrate) converted to MP2 at 224 kbps, does it affect the quality ? ie, things like fade or bass and all that parameters from audio ?
that's because I have sources with Audio with low bitrates, and I set CCE to encode at 224 Kbps
is the source audio mp3? It's lossy so if you convert it to mp2 yes quality will be affected and will sound worse than the original audio.
If this is for DVD why not convert to 2 channel ac3 using besweet? It is a better codec than mp2 and to my ears sounds a lot better than mp2 when encoded at the same bitrates.