Arch Linux

yomtendok

Member

Registered: 2007-10-21

Posts: 15

ffmpeg doesn't recognize my bitrates!

I'm looking to free up some room on my hard drive, so I decided I'm going to put a couple of videos onto DVDs.  The problem is, the trusty program I've been using for the last year or so isn't working how it's supposed to be.

Using the -b option (as well as -ab, for audio) simply doesn't work.  Using the preset "-target ntsc-dvd" does, but I'm not looking to use that.  The thing is, I'm trying to squeeze two movies onto one DVD.  The initial quality of the videos isn't all that great, either, so I'm not worried about the picture degrading; using a bitrate of about 1500kb/s versus the default 6000 that the -target option uses is totally adequate. 

This didn't cause a huge problem, since I can still use mencoder to encode my video, but to get ac3 audio, this is a problem.  I've tried using mp2 audio a handful of times for DVDs and I have always had sub-par results.  Again, since I'm trying to save space, I am looking to encode to 224 kb/s AC3 instead of 448, and again, ffmpeg isn't recognizing "-ab" and will default to 64.

I've tried a few things to fix the problem, but I'm not sure what else I can do.  I'm using the default 20070505-4 version in the repos, but I've also tried building with ABS, building ffmpeg-svn from AUR, and compiling from sources from the mplayer website.  Nothing has worked.

Any suggestions?

yomtendok

Member

Registered: 2007-10-21

Posts: 15

Re: ffmpeg doesn't recognize my bitrates!

Seems that I was simply forgetting to put a k after the number.  I've been using Ubuntu the whole time I've been familiar with ffmpeg, so I guess the version they've always had in their repos didn't require the k. 

Anyways, problem solved... I just couldn't delete the thread.

thayer

Fellow

From: Vancouver, BC

Registered: 2007-05-20

Posts: 1,560

Website

Re: ffmpeg doesn't recognize my bitrates!

Thanks for the tip, yomtendok... I've been experiencing this very issue all week long.  All of the tutorials I've seen omit the 'k' as well.

---

thayer williams ~ cinderwick.ca

skottish

Forum Fellow

From: Here

Registered: 2006-06-16

Posts: 7,942

Re: ffmpeg doesn't recognize my bitrates!

If you're ever having problems with FFmpeg, it's best to check the on-screen documentation:

[skottish@localhost ~]$ ffmpeg | grep -i bitrate
FFmpeg version SVN-r10893, Copyright (c) 2000-2007 Fabrice Bellard, et al.

--snip--

-b                 <int>   E.V.. set bitrate (in bits/s)
-ab                <int>   E..A. set bitrate (in bits/s)
-bt                <int>   E.V.. set video bitrate tolerance (in bits/s)
-maxrate           <int>   E.V.. set max video bitrate tolerance (in bits/s)
-minrate           <int>   E.V.. set min video bitrate tolerance (in bits/s)
-mepc              <int>   E.V.. motion estimation bitrate penalty compensation (1.0 = 256)

Notice that all the lines are in bits/s.

As you use the newer versions, you'll find that a whole bunch of codecs have been renamed as well. In versions newer than what's in the repos it's even more pronouced.  FFmpeg has been standardizing everything to give one concise user interface, as well as one developer interface.