problems encoding stereo ac3 with ac3enc

[LigH]

Thank you very much for providing this binary, although you obviously are rather a Linux fan than Windows...

Now I'll have to check if this ffmpeg version is also able to encode MPEG-2 video: No matter which bitrate parameters I tried for the EXE included in ffmpegGUI 0.3, it always assumed "2 kbps". But that will be another thread, I'd propose.

[P0l1m0rph1c]

Hmm...how about a build of ac3enc.dll for Besweet, with this new code (patched ac3enc.c)? The source of the plugin is available at DspGuru's page, it's just compile. Unfortunately, I haven't managed to compile it successfully yet. So, a build would be very, very apreciated.

BTW: today I downloaded latest FFmpeg's CVS snapshot, and ac3enc.c had some changes. Probably the changes were already commited.

[LnxPeng]

I just caught wind that the team is not using the sourceforge CVS, even though it exists.....maybe that is my problem....

[Haaan]

By the way, I'm interested in the last version of avcodec.dll, if you can compile it, it's a part of ffmpeg. Please PM me.

[LnxPeng]

Greetings All,

My school does all programming on a SPARC running on Solaris. As such I have never compiled a dll. Therefore I would be happy to provide compiles but need some time to learn the ins and outs of dynamic link libraries(and I need to buy VC++ ). But I am working on it.

[LnxPeng]

I have downloaded the latest ac3enc.c off of the new CVS servers and recompiled ffmpeg 0.4.8 with the latest and greatest ac3enc. I had to edit it by hand to get it to compile (I uploaded my source that I edited with it).

@DSPGuru...would it be alright if I did recompile ac3enc as a BeSweet dll? I would note that no one should complain to you about it if there are probs (That is of course contingent on the fact that I can find my old VC6 cd.)

Lastly, will BeSweet resolve symbols in a dll compiled with MinGW? The site has directions on interoperability here:
http://www.mingw.org/mingwfaq.shtml#faq-msvcdll

Finally, the new binaries can be found here:
http://www.cbu.edu/~nwebb/ac3.html

[DSPguru]

try out v1.5b26.

[LigH]

in 22nd March 2004, DSPguru wrote :

"i'll be away for almost 10days, (going to some conference),
so please be patient."

thanks for the new beta and for your precision too (10 days)!

[LnxPeng]

Wow thanks! I apriciate it

[P0l1m0rph1c]

Great news!

Thanks DSPGuru, for all your efforts. This shall be very useful.

Regards

[P0l1m0rph1c]

OK, so far, so good. I've been doing some encodes in ac3 (both stereo and 5.1) and there weren't problems with compatibility so far.

I'll keep testing.

[tiki4]

Great news. It would be nice to include b26 in the next release of AVI2DVD (DVD2SVCD) to get DVD with AC3 on the fly.

Cheers and thanks Dg,

tiki4

[Corn]

Did a few quick test with the AC3->AC3 convertion. Looks like it scales the audio the right way now and normalize it correctly

BTW when you get those overflows in the log file as it was before
the audio not only clips but it wraps du to the float to short (int) conversion and generate massive distorsion as a result instead of just clipping

DSPguru_API void Standard( float* buffer,int size)
{
static unsigned char frame[AC3_MAX_CODED_FRAME_SIZE];
static short samples[6*AC3_FRAME_SIZE];
int ret, i,j=0;

// process the block from BeSweet
for(i=0;i!=size;i++)
{ /* L C R SL SR (+LFE) */
****----> samples[i]=(short)(32767*buffer[i]);
}
ret = AC3_encode_frame(ctx, frame,i, samples);

// return the block to BeSweet
BS_Output(frame,ret);
}

buffer[i] must not be lower than -1.0 and not greater than 1.0
or it will wrap with massive distorsion as a result.

But as long as one normalize and it work as it looks like now there should not be a problem
Just be aware that if you get a overflow warning in the log file.

Hope this might shed some light

cheers

[Tsui]

The volume-bug is still there, right?

Input : normalized 2 channel wav
Output : the volume of the ac3 is at 50%

[Corn]

Even with the -azid ( -g max) switch? that should normalize it...

BTW are you using besweet GUI or AC3machine?
I only tested with AC3machine... and it looks ok there

[Tsui]

I thing that '-azid ( -g max)' ist only for ac3 input and not for wav input, right or wrong?

[weirdaznboi923]

if you have massive issues, try using sonic foundry soft encode. its dead for quite a while, but you might be able to find a copy for $2 at a flea market or ebay. i got my CD from the annual boy scouts flea market we have here !

[Tsui]

I don't have problmes to encode ac3 with other tools.
The point ist that there seems to be a problem with ac3enc that should be fixed.

[P0l1m0rph1c]

This was why DSPGuru removed ac3enc support from Besweet, guys...

People start complaining about things that have nothing to do with Besweet or DSPGuru.

If you think ac3enc should be fixed, please tell these issues to the ffmpeg guys, not here.

Regards