mencoder/lame vbr questions

nexx · 4th November 2004, 06:28

I've been experimenting with using mencoder to create DVDrips and I've been very happy with the results. But there's a new things I want cleared up regarding mp3/vbr audio.
I've been using mencoder under WindowsXP but thought it would apply here anyway.

1) How well does mencoder handle creating avi files with MP3 VBR audio? All the guides I've read use CBR.
In my tests they play back fine in mplayer and various other windows/linux players...maybe I'm missing something?

2) In the manual, it shows diferent vbr types (vbr=x) - cbr,mt,rh(default),abr,mtrh.
What is the difference between the types and which one best suits my purposes?

I've been using -lameopts q=0:aq=0:preset=medium

Any help appreciated :)

Joe Fenton · 6th November 2004, 02:52

Well, cbr is constant bit rate, and abr is average bit rate. I've never seen an explanation of the others because no one uses then. Nearly everyone use abr. This gives more bits to more complex sections and less bits to less complex sections while striving to keep the bitrate on average to what you specify. This is usually what you want for audio.

If you are making a video cd, you HAVE to use cbr as that is the only type of audio allowed by spec. Old AVI players also can't handle anything other than cbr. So if you are making a VCD or trying for the best compatibility possible, you'd go with cbr. In all other cases, you go with abr. You'll notice in the docs that most all the presets are abr at different average bitrates.

echo · 6th November 2004, 22:38

1) No, you're not missing a thing. Avi/mp3-VBR play and encode just fine with mplayer/mencoder. The reason all the guides use CBR is because you can't set the exact target bitrate with VBR and you might get slight fluncuations with ABR. Plus some standalones might have some problems with VBR/ABR I think but don't take my word for it.

2) CBR is constant bit rate, ABR is average bitrate, meaning that you set a target bitrate and lame tries to match it. MT, RH, and MTRH are what is also called VBR-old, VBR-new and VBR-mixed old and new codes (I don't really remember which is which). Using VBR (as you are doing since preset medium is VBR) you don't have any control on the target bitrate.

BTW, I think that using mp3 on encodes is a waste of space if you are not going to use a standalone. I prefer encoding audio with vorbis -q 2 or 3 and mux it all in matroska.

Joe Fenton · 7th November 2004, 00:45

Yep, echo has that right. Always use ogg-vorbis at quality 2 or 3 for audio. Uses fewer bits and sounds better. The choice between ogm and Matroska is always hotly debated, but either one will do fine. I haven't encoded to avi in a 'coon's age.

nexx · 9th November 2004, 15:16

Thanks guys

4th November 2004, 06:28	#1 \| Link
nexx Registered User Join Date: Sep 2004 Location: Brisbane, Australia Posts: 74	mencoder/lame vbr questions I've been experimenting with using mencoder to create DVDrips and I've been very happy with the results. But there's a new things I want cleared up regarding mp3/vbr audio. I've been using mencoder under WindowsXP but thought it would apply here anyway. 1) How well does mencoder handle creating avi files with MP3 VBR audio? All the guides I've read use CBR. In my tests they play back fine in mplayer and various other windows/linux players...maybe I'm missing something? 2) In the manual, it shows diferent vbr types (vbr=x) - cbr,mt,rh(default),abr,mtrh. What is the difference between the types and which one best suits my purposes? I've been using -lameopts q=0:aq=0:preset=medium Any help appreciated :)

6th November 2004, 02:52	#2 \| Link
Joe Fenton Registered User Join Date: Jul 2003 Location: In a house. Posts: 663	Well, cbr is constant bit rate, and abr is average bit rate. I've never seen an explanation of the others because no one uses then. Nearly everyone use abr. This gives more bits to more complex sections and less bits to less complex sections while striving to keep the bitrate on average to what you specify. This is usually what you want for audio. If you are making a video cd, you HAVE to use cbr as that is the only type of audio allowed by spec. Old AVI players also can't handle anything other than cbr. So if you are making a VCD or trying for the best compatibility possible, you'd go with cbr. In all other cases, you go with abr. You'll notice in the docs that most all the presets are abr at different average bitrates.

6th November 2004, 22:38	#3 \| Link
echo Registered User Join Date: Jan 2003 Posts: 130	1) No, you're not missing a thing. Avi/mp3-VBR play and encode just fine with mplayer/mencoder. The reason all the guides use CBR is because you can't set the exact target bitrate with VBR and you might get slight fluncuations with ABR. Plus some standalones might have some problems with VBR/ABR I think but don't take my word for it. 2) CBR is constant bit rate, ABR is average bitrate, meaning that you set a target bitrate and lame tries to match it. MT, RH, and MTRH are what is also called VBR-old, VBR-new and VBR-mixed old and new codes (I don't really remember which is which). Using VBR (as you are doing since preset medium is VBR) you don't have any control on the target bitrate. BTW, I think that using mp3 on encodes is a waste of space if you are not going to use a standalone. I prefer encoding audio with vorbis -q 2 or 3 and mux it all in matroska.

7th November 2004, 00:45	#4 \| Link
Joe Fenton Registered User Join Date: Jul 2003 Location: In a house. Posts: 663	Yep, echo has that right. Always use ogg-vorbis at quality 2 or 3 for audio. Uses fewer bits and sounds better. The choice between ogm and Matroska is always hotly debated, but either one will do fine. I haven't encoded to avi in a 'coon's age.

9th November 2004, 15:16	#5 \| Link
nexx Registered User Join Date: Sep 2004 Location: Brisbane, Australia Posts: 74	Thanks guys