[Fame-devel] Re: fame audiobitrate parameter

[Vivien C. <viv...@en...>]

On 12 Feb 2002, Patrick Dreker wrote:

> Hello...

Hi

> Yesterday I stumbled across your fame/libfame software and I must say,
> that this is the only realtime MPEG1 encoder, which I got to run
> reliably (meaning: no framedrops, no segfaults and so on).
> Very nice program, indeed.

Thanks!
 
> There was one minor annoyance: the bitrate of the captured audiostream
> is (or should I say: was...) hardcoded to 64kBit/s, which was to low for
> my requirements (I want to capture full resolution PAL TV with good
> audio and video quality).

Sure, fame is a really simple hack to provide a 'frontend' to libfame :)

> So I took a look into the source code and I found it to be quite
> readable and I added a parameter to pass fame the bitrate to use for the
> mp3 Stream.
> 
> Attached you will find patches against libfame-0.8.9/src/fame.h
> (libfame_audiobitrate.patch) and against fame-0.8.9/src/fame.c
> (fame_audiobitrate.patch). The patches implement a "-u" and
> "--audiorate" option which take the audiobitrate in kBits/s ("-u"
> because "-a" was already taken), add the appropriate usage info, and
> extend libfame to correctly initialize the extended fame_parameter_t.
> 
> If the option is omitted fame uses the default of 64 kBit/s.
> I have briefly tested the changes and they seem to work as intended.
> 
> I would like to hear back from you.

Hmm ok, I wouldn't add audio parameters to libfame actually as it is only
a video encoding library, i.e. fame uses liblame and libfame, but libfame
doesn't use lame.. Thus I've made audiobitrate a global variable in fame.
I've also changed the bitrate unit for audio to bits/s to be consistent
with the bitrate for video (in bits/s too.. BTW I've found a typo in the
usage help, thx!)
Thanks for your patch, it's applied in latest CVS.

> Another question: what tool would you recommend to multiplex the video
> and audiostreams? 

.. actually.. I don't know :)

 I've heard someone transcoding mp3 back to mp2 (thus I should add mp2
support in fame), and then using tools for building VCDs. I've a package
in my Debian called vcdtools and including vcdmplex which I know to work
with mp2 and mpg video files.

> I tested transcode and mplex (from the MJPEG Tools)
> and both don't seem to do the right thing...

BTW, I've a patch (from Yannick Vignon) for transcode to add support for
fame, maybe you're interested. I don't know if transcode supports capture,
but if you want to code at PAL size and have huge CPU power, you can
create DivX compatible AVIs using fame (faster, more free :)),
that will save a lot of disk space (MPEG4)... Consider the patch under
GPL. You'll need the latest libfame CVS version for this to work however. 
Feel free to test/criticize :)
(I'll put that on the web page when I get a chance)
I don't know much about mplexs, I've been focussing too much on video :)

regards,
Vivien Chappelier.