[FFmpeg-devel] [RFC] ffserver stream checks

Howard Chu hyc
Thu May 20 16:31:58 CEST 2010

Ronald S. Bultje wrote:
> Hi,
> On Thu, May 20, 2010 at 10:03 AM, Howard Chu<hyc at highlandsun.com>  wrote:
>> I'd like to be able to treat the ffserver config as more of a template, and
>> allow the ffmpeg commandline to override some of the settings, or at least
>> fill in missing ones. Currently it looks like whatever ffmpeg receives from
>> ffserver completely replaces all of ffmpeg's option settings. Suggestions?
> I think that's intentional, if you check ffmpeg.c there's specific
> code for that. It would be weird to do otherwise because you'd have a
> conflict or confusion for the user:
> - what if ffserver.conf specifies bitrate=X and ffmpeg's commandline
> options specify bitrate=Y, where X!=Y? Right now it's clearly defined
> that ffserver.conf takes precedence.
> - both ffserver.conf and ffmpeg have bitrate options. Which one should
> the user use to specify bitrate? Right now it's clearly defined that
> it's ffserver.conf for this particular case.
> I'm not against allowing ffmpeg to override certain ffserver settings
> if there is a clear demand for that, but please mae sure that it
> doesn't become confusing or conflicting for the user.

Agreed. I would expect bitrate to be one that ffserver always defines; that's 
really the most crucial parameter for a real time stream. But some other 
things might reasonably be left empty/default for ffmpeg to fill in. I used 
frame rate as an example above; one might also want to override the frame 
dimensions. E.g., I might want to send 4:3 video at one time, and 16:9 at 
another time. It should always fit into a defined maximum window size, but 
other than that, it should be free to vary.

Perhaps it should just be an option on the <Feed> specification: some-keyword 
== use settings from ffmpeg ...

   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/

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