HydrogenAudio

Lossy Audio Compression => MP3 => MP3 - General => Topic started by: vladimirovich on 2002-04-25 08:27:38

Title: MP3pro
Post by: vladimirovich on 2002-04-25 08:27:38
Is there any ACM decoder that allows using Mp3 pro in DivX movies?
Title: MP3pro
Post by: Benjamin Lebsanft on 2002-04-25 12:43:10
why would you want to do this. Vorbis is the better and free alternative and there are already programs to create movies with vorbis soundtracks.

To answer your question: no and i doubt that mp3pro support will be that great and i have to admit that i'm in no way sorry for that as i consider mp3pro rubbish
Title: MP3pro
Post by: dev0 on 2002-04-25 12:55:29
Even if you get the audio encoded as mp3pro (should be possible) and muxed, you will encounter a bigger problem: There is no DSF (DirectShowFilter) for mp3pro available and mp3pro won't work with the regular MP3 ACM/DSF.
So better stick to *.avi with lame or *.ogm with vorbis.
X
Title: MP3pro
Post by: vladimirovich on 2002-04-25 16:01:35
Well, I've tested mp3 pro implementation in CoolEdit 2.0 and found it very interesting. By the way, It's only encoder that allows mp3Pro VBR realization.

I've tested this codec, and found that the music sounds "little different" from the original, but still very good. The bitrate was about 130 kbps.

When we speak about div'x, we should notice, that we must mean low bitrates, 128 or even lover. MP3Pro's SBR is the only technology, that allows "not 16Khz lowpassed" signal at those bitrates.

Of course, full bandwidth couldn't mean quality (VQF is an example), but still...

By the way, is the Mp3 pro format open? If someone want to write his own encoder, could he do it or not?
Title: MP3pro
Post by: Benjamin Lebsanft on 2002-04-25 16:09:21
at bitrates like 130 kbps vorbis or even mp3 sounds much better because SBR destroys dynamic range.

mp3pro isnt open and the license fee for firms is "only" 375000$ 

So vorbis should sound much better at 130 kbps and even lower bitrates
Title: MP3pro
Post by: Benjamin Lebsanft on 2002-04-25 16:10:53
and vorbis doesn't lowpass at 16kHz neither
Title: MP3pro
Post by: HotshotGG on 2002-04-27 08:36:54
Vorbis Lowpass Filtering:

As of the current RC3 release Vorbis has an IIR lowpass filter implementation that is fixed for a given subjective quality setting -q, not bitstream dependent. The lower the quality setting the more IIR lowpass filtering that is applied, with the exception of the -q setting that gives an average bitstream of around ~120 kbps and up at which point I believe the IIR lowpass filtering stops at around 18.3 kHz, which includes lossy and lossless channel coupling mechanisms as well. This filter was not present in the previous release candidates RC2 and happened to be a hack that had worked from my understanding. Any audio past 16 kHz as far as I am concerned useless to the human ear, unless there happen to be a extrenous number of any tonal noises past 8 kHz at which filtering would not be a good idea, but this happens very rarely. There may also be a extrenous number of transients, which should not be greatly effected by filtering and should need only be present up to about 16 kHz any noise past that is nearly undectable to the human ear and useless otherwise and need not have a great impact on subjective quality.

SBR:

Spectral Band Replication is based upon the idea encoding all noise up to about 8 kHz in an MDCT anaylsis filterbank than taking the original 8 kHz of the spectrum and as you know rescontructing it to produce the rest to the spectrum up to about 16 kHz for lower-bitstreams 64 kbps. It gives poor results at higher bitstreams. I have yet to hear an example of it in action, but once again if I am not mistaking Fraunhoffer plans to use SBR in there MPEG-4 AAC designs.

If I where looking for a lower-bitstream in an audio codec to incoporate with DIVX MPEG-4 Video Codec. I would probably either have to choose between Ogg Vorbis or MPEG-4 AAC. If it where me I might eventually take MPEG-4 AAC for two simple reasons, it's a standard even though a patented one along with the codec that works with the standard MPEG-4 video codec and Ogg Vorbis bitstreams will be more well suited when they are multiplex with promising new video codec of that Ogg Tarkin, but that is just my opinion you may think Vorbis sounds better with DIVX video streams.

Some people don't speak english that well. I apologize for all the comma's I hadn't proofread this post.
Title: MP3pro
Post by: NeoRenegade on 2002-05-01 19:36:57
Can we please practise proper spelling and punctuation on these fora?
Title: MP3pro
Post by: HotshotGG on 2002-05-01 19:56:23
It could be worse. I could just slang words left and right . A spell checker that worked may also be nice.