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

[Roman Shaposhnik]

On Wed, 2008-01-09 at 16:16 +0100, Alessandro Sappia wrote:
> HI all,
> Attached a patch which reformat code to be as suggested
> by roman.

  In general it seems to be ok. I'm going to commit the last
version of it (with the typo fixed) shortly.

> 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?

> 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.

> Roman, did you check my patch for fps and fmt default value handling ?
> I ask this because it happened to me that

  I didn't apply your patch (it was broken). I fixed the bug there
myself.

> $ ./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

> Related to that, the DC1394 standard for format0 define fps up to 240fps
> per second, may these speed useful in ffmpeg ?

  Perhaps.

> I was thinking about using format7 acquire mode, but while it gives us
> the ability of asking the cam for a precise fps, this has the overload of
> having to do the debayer in software. what do you think about it ?

  Its all about you sending patches ;-)

Thanks,
Roman.