[FFmpeg-devel] [PATCH] new version of libdc1394 - resubmitting after review

Alessandro Sappia a.sappia
Fri Jan 11 03:06:47 CET 2008

Sorry, last mail was sent just to Roman, and was missing the patch.

Roman Shaposhnik ha scritto:
> On Wed, 2008-01-09 at 16:16 +0100, Alessandro Sappia wrote:
>   In general it seems to be ok. I'm going to commit the last
> version of it (with the typo fixed) shortly.
good :)
>> guid is a unit64_t
>> unit is an int
>> one should eventually add a command line option for show
>> connected guids and how many unit that guid has (to select
>> proper camera)
>> may I add such command line options ?
>   My personal observation is that ffmpeg doesn't allow for
> such browsing. You're supposed to know well in advance
> the precise "address" of the equipment you're going to
> capture A/V streams from. Adding such a tool to the tools/
> sub-directory could be fine. But that makes me wonder --
> aren't there such tools already available as part of the
> libdc* packaging?
nope: there are just a few examples of how to use libdc1394.
The main client for libdc1394 is coriander, a GTK tool for acquire,
debayer, save and show a camera per client.
well, except for the browsing part, that is something we could
not deal with, I think that a -guid XXXXXXXX -unit X parameters
would be useful.
Without such options ffmpeg is limited to the first camera connected.
While it's true that 90% of firewire configuration  have just
one camera, with more than one camera we just select first camera
and work with it.

>> Useful thing should be shutter time and some controls (white balance,
>> gain, transmission speed, etc...)
>> Should we expose them to ffmpeg users ?
>   Again, IMHO a separate tool would be a better approach here.
good, I'll think about it, and I'll come back with something IF I find
useful :P

>> $ ./ffplay -f libdc1394 /dev/video1394/1
>> FFplay version git-06d4c94, Copyright (c) 2003-2008 Fabrice Bellard, et al.
>>   configuration: --enable-decoders --enable-encoders --enable-muxers
>> --enable-demuxers --enable-parsers --enable-protocols --enable-bsfs
>> --enable-indevs --enable-outdevs --enable-libdc1394 --disable-strip
>>   libavutil version: 49.6.0
>>   libavcodec version: 51.49.0
>>   libavformat version: 52.3.0
>>   built on Jan  9 2008 05:42:10, gcc: 4.1.3 20070929 (prerelease)
>> (Ubuntu 4.1.2-16ubuntu2)
>> [libdc1394 @ 0x84181b4]Can't find matching camera format for uyvy422,
>> 320x240 at 25000:1000fps
>> /dev/video1394/1: Error while opening file
>> $
>> This happens because DCcamera in Format0 can't acquire at any speed,
>> but there are some fixed. It seems that ffplay asks for 25 fps while 25 fps
>> is not a standard acquiring fps for dc1394.
>   That is correct. But there's nothing I can do to fix it, short of
> patching ffplay.c
should we force the best matching fps (30 in this case) ?
>> Related to that, the DC1394 standard for format0 define fps up to 240fps
>> per second, may these speed useful in ffmpeg ?
>   Perhaps.
Attached a trivial patch which enables higher frame-rate.
(patch dependendent by the  Message-ID: <4784E54D.2050707 at ngi.it>)
I did it because you told me you're going to commit that patch.



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