[FFmpeg-devel] ffmpeg-devel Digest, Vol 26, Issue 187

Thu May 17 16:07:42 CEST 2007

-----Original Message-----
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Sent: 17 May 2007 13:50
To: ffmpeg-devel at mplayerhq.hu
Subject: ffmpeg-devel Digest, Vol 26, Issue 187

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Today's Topics:

   1. Re: Issue with Capture between SVN -r8222 and SVN -r8634
      (Luca Abeni)
   2. Re: [Ffmpeg-devel] [RFC] Reimplemented functions
      (Alex Beregszaszi)
   3. Re: Issue with Capture between SVN -r8222 and SVN -r8634
      (Luca Abeni)
   4. Re: Issue with Capture between SVN -r8222 and SVN -r8634
      (Luca Abeni)
   5. Some patches for v4l2 defaults (Luca Abeni)
   6. Re: [PATCH] mdct fft dependencies (Aurelien Jacobs)
   7. Re: [PATCH] mdct fft dependencies (Benjamin Larsson)
   8. Re: [PATCH] Use DECLARE_ALIGNED_16 in libavcodec/ppc/
      (Guillaume POIRIER)
   9. Re: [PATCH] mdct fft dependencies (Aurelien Jacobs)

----------------------------------------------------------------------

Message: 1
Date: Thu, 17 May 2007 13:04:15 +0200
From: Luca Abeni <lucabe72 at email.it>
Subject: Re: [FFmpeg-devel] Issue with Capture between SVN -r8222 and
	SVN -r8634
To: FFmpeg development discussions and patches
	<ffmpeg-devel at mplayerhq.hu>
Message-ID: <464C36AF.3060304 at email.it>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi,

Nikns Siankin wrote:
[...]
>> Tried -tvstd - had no effect
> make sure you set -tvstd in the BEGINNING in command line.
> this is some stupid undocumented behaviour, that isn't self intuitive 
> for normal users.
About the "stupid" adjective, everyone is free to have his own
opinions... But "undocumented" seems to be wrong. Quoting the ffmpeg
documentation page (http://ffmpeg.mplayerhq.hu/ffmpeg-doc.html):
 > The generic syntax is:
 >
 > ffmpeg [[infile options][`-i' infile]]... {[outfile options]
outfile}...
 >
 > As a general rule, options are applied to the next specified file.
 > Therefore, order is important, and you can have the same option on
the > command line multiple times. Each occurrence is then applied to
the  > next input or output file.
So, I would not call this an "undocumented behaviour".

				Luca

------------------------------

Message: 3
Date: Thu, 17 May 2007 13:06:14 +0200
From: Luca Abeni <lucabe72 at email.it>
Subject: Re: [FFmpeg-devel] Issue with Capture between SVN -r8222 and
	SVN -r8634
To: FFmpeg development discussions and patches
	<ffmpeg-devel at mplayerhq.hu>
Message-ID: <464C3726.70309 at email.it>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi,

Mike Martin wrote:
[...]
> Will try patch when I get home.
> 
> Tried -tvstd - had no effect
> 
> Didn't try -vc because
> 
> 
> `-vc channel' 
> Set video grab channel (DV1394 only).
This is an error in the documentation; I'll fix it.
In current svn, "-vc" also works for the video4linux2 input.

				Luca

------------------------------

Message: 4
Date: Thu, 17 May 2007 13:10:15 +0200
From: Luca Abeni <lucabe72 at email.it>
Subject: Re: [FFmpeg-devel] Issue with Capture between SVN -r8222 and
	SVN -r8634
To: FFmpeg development discussions and patches
	<ffmpeg-devel at mplayerhq.hu>
Message-ID: <464C3817.10208 at email.it>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi,

Mike Martin wrote:
[...]
> As undocumented by beginning would it be
> 
> Ffmpeg -tvstd -f video4linux2 -i /dev/video0 etc
As per ffmpeg's manual, "-tvstd" wants a parameter:
 > `-tvstd standard'
 >    Set television standard (NTSC, PAL (SECAM)).
So, try
./ffmpeg -tvstd PAL -f video4linux2 -i /dev/video0 ...
(instead of "PAL", use the name of the video standard you want to set. 
It must be a video standard name recognised by the v4l2 driver)

I know - this was just an example giving enough detail

				Luca

------------------------------

Message: 5
Date: Thu, 17 May 2007 14:08:48 +0200
From: Luca Abeni <lucabe72 at email.it>
Subject: [FFmpeg-devel] Some patches for v4l2 defaults
To: ffmpeg-devel at mplayerhq.hu
Message-ID: <464C45D0.4040301 at email.it>
Content-Type: text/plain; charset="iso-8859-1"

Hi all,

right now, ffmpeg always tries to set the video standard (default: NTSC)
and the video input (default: 0) when capturing v4l2 video.

After applying the attached patches, ffmpeg will set video standard and
input only if explicitly requested, leaving them as they are by default.

default_video_standard.diff: sets video_standard default to NULL, which
means "do not set a video standard (use the currently set one)"

dv1394_support_default_channel.diff: since "0" is a valid video input
number for v4l2, "-1" will become the default meaning "do not set the
video channel (use the currently set one)". This patch adjusts dv1394.c
to cope with "channel == -1"

default_channel.diff: set the default channel to -1.

These patches are by Limin Wang, I just split and slightly modified
them.

I think default_video_standard.diff should be pretty safe, and I'll
apply it on monday if noone objects. For
dv1394_support_default_channel.diff, I'd like to have the ok from the DV
maintainer, and I'll apply default_channel.diff as soon as
dv1394_support_default_channel.diff will be in.

			Thanks,
				Luca

thanks

as an aside the docs say this

2.1 Video and Audio grabbing
FFmpeg can grab video and audio from devices given that you specify the
input format and device. 

ffmpeg -f audio_device -i /dev/dsp -f video4linux2 -i /dev/video0
/tmp/out.mpg

Note that you must activate the right video source and channel before
launching FFmpeg with any TV viewer such as xawtv
(http://bytesex.org/xawtv/) by Gerd Knorr. You also have to set the
audio recording levels correctly with a standard mixer. 

so the docs should have been changed to reflect this (now reverted)
change

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