I know its long time since this case was posted but i am facing the same
problem now. So did you find any possible solution for it as it could be
helpful?
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- Original Message -
From: Roger Pack rogerdpa...@gmail.com
To: This list is about using libavcodec, libavformat, libavutil,libavdevice
and libavfilter. libav-user@ffmpeg.org
Sent: Thursday, August 02, 2012 2:48 PM
Subject: Re: [Libav-user] Why does av_seek_frame() not seek
On Sun, Aug 5, 2012 at 5:51 AM, Don Moir donm...@comcast.net wrote:
I see this has been reported as ticket #1575 but why this is reported as an
enhancement and not a bug, god only knows.
This should not be a documentation issue and in my way of thinking, its a
bug. We don't need gray areas
- Original Message -
From: Michael Bradshaw mbrads...@sorensonmedia.com
To: This list is about using libavcodec, libavformat, libavutil,libavdevice
and libavfilter. libav-user@ffmpeg.org
Sent: Sunday, August 05, 2012 11:09 AM
Subject: Re: [Libav-user] Why does av_seek_frame() not seek
Could you provide a sample that does not seek to a keyframe with
ffmpeg -ss x -i input out.png
(I tested this yesterday on random mpeg2video samples and afaict,
it did work.)
With me, I get this:
with this file: http://rogerdpack.t28.net/incoming/sintel.mpg
$ ffmpeg -i sintel.mpg -vcodec
$ ffmpeg -i sintel.mpg -vcodec copy -acodec copy -ss 90.0 starting_at_90.mpg
then try and use it again:
$ ffmpeg -i starting_at_90.mpg -vframes 1 -f image2 -an snap.jpg
I get this warning message:
[mpeg2video @ 01f09860] warning: first frame is no keyframe
Anybody know if this is
On Thu, Aug 2, 2012 at 12:10 PM, Roger Pack rogerdpa...@gmail.com wrote:
Could you provide a sample that does not seek to a keyframe with
ffmpeg -ss x -i input out.png
(I tested this yesterday on random mpeg2video samples and afaict,
it did work.)
With me, I get this:
with this file:
I believe that does no seeking there. Putting -ss after the input will cause
ffmpeg to demux up to the requested timestamp, so it's not quite related to
seeking (putting -ss before the input will seek the input file).
Since -a/vcoded copy avoids re-encoding, it just copies the packets
On Thu, Jul 19, 2012 at 2:01 PM, Michael Bradshaw
mbrads...@sorensonmedia.com wrote:
[...]
I guess we should define what would be considered erroneous seeking
to make sure I'm on the same page as everyone, as it's possible I'm
not. Would these be considered problematic:
1) Seek is performed,
Michael Bradshaw mbradshaw@... writes:
Anyone have any answers on these two things? If the answer to the
above would be yes can anyone else verify that ffmpeg -dump
-loglevel debug -ss 38 -i 704x480-m2v-ac3.mpg -vframes 1 out.jpg does
not seek to a keyframe?
As said, afaict it does seek to a
On Mon, Jul 23, 2012 at 11:12 AM, Carl Eugen Hoyos ceho...@ag.or.at wrote:
Michael Bradshaw mbradshaw@... writes:
Anyone have any answers on these two things? If the answer to the
above would be yes can anyone else verify that ffmpeg -dump
-loglevel debug -ss 38 -i 704x480-m2v-ac3.mpg
On Mon, Jul 23, 2012 at 7:12 PM, Carl Eugen Hoyos ceho...@ag.or.at wrote:
Michael Bradshaw mbradshaw@... writes:
Anyone have any answers on these two things? If the answer to the
above would be yes can anyone else verify that ffmpeg -dump
-loglevel debug -ss 38 -i 704x480-m2v-ac3.mpg
Hendrik Leppkes h.leppkes@... writes:
Anyone have any answers on these two things? If the answer to the
above would be yes can anyone else verify that ffmpeg -dump
-loglevel debug -ss 38 -i 704x480-m2v-ac3.mpg -vframes 1 out.jpg does
not seek to a keyframe?
As said, afaict it does seek
On Mon, Jul 23, 2012 at 12:50 PM, Carl Eugen Hoyos ceho...@ag.or.at wrote:
[...]
You are probably right, I assumed that from a users' perspective,
the only relevant question is if above command line returns a gray
frame or the next keyframe.
Ah, I see. I think that's where the confusion is
- Original Message -
From: Michael Bradshaw mbrads...@sorensonmedia.com
To: This list is about using libavcodec, libavformat, libavutil,libavdevice
and libavfilter. libav-user@ffmpeg.org
Sent: Monday, July 23, 2012 3:10 PM
Subject: Re: [Libav-user] Why does av_seek_frame() not seek
Afair, Reimar believes the seek function should not try hard to find
a keyframe because seeking faster is more important.
This most important thing is consistency. In my case (and anyone really),
that means when I do a seek, the first returned packet should be a key frame
packet and the time
Hendrik Leppkes h.leppkes@... writes:
On Thu, Jul 19, 2012 at 8:18 AM, Carl Eugen Hoyos wrote:
Michael Bradshaw mbradshaw at ... writes:
But when I seek, the first packet returned out of the demuxer is
not a keyframe packet, and I have to read several (~45ish) packets
until I encounter a
On Thu, Jul 19, 2012 at 8:31 AM, Carl Eugen Hoyos ceho...@ag.or.at wrote:
Isn't this necessary for some codecs / at least for H264? Wouldn't
the API do exactly the same?
Sure, if you end up seeking to a non-keyframe, it should not decode garbage
frames.
The point here is that we would want
On Thu, Jul 19, 2012 at 9:25 AM, Carl Eugen Hoyos ceho...@ag.or.at wrote:
So if the file is ~2GB and (as a user) I seek approximately to
the middle of the video and decide to seek back then, the
video should be decoded from the beginning to find the keyframe
before the position I want to seek
On 07/19/2012 09:25 AM, Carl Eugen Hoyos wrote:
Hendrik Leppkes h.leppkes@... writes:
On Thu, Jul 19, 2012 at 8:31 AM, Carl Eugen Hoyos wrote:
Isn't this necessary for some codecs / at least for H264?
Wouldn't the API do exactly the same?
Sure, if you end up seeking to a non-keyframe, it
On Thu, Jul 19, 2012 at 12:18 AM, Carl Eugen Hoyos ceho...@ag.or.at wrote:
Michael Bradshaw mbradshaw@... writes:
But when I seek, the first packet returned out of the demuxer is
not a keyframe packet, and I have to read several (~45ish) packets
until I encounter a keyframe.
Could you
Michael Bradshaw mbradshaw@... writes:
But when I seek, the first packet returned out of the demuxer is
not a keyframe packet, and I have to read several (~45ish) packets
until I encounter a keyframe.
Could you provide a sample that does not seek to a keyframe with
ffmpeg -ss x -i
- Original Message -
From: Michael Bradshaw mbrads...@sorensonmedia.com
To: This list is about using libavcodec, libavformat, libavutil,libavdevice
and libavfilter. libav-user@ffmpeg.org
Sent: Thursday, July 19, 2012 1:13 PM
Subject: Re: [Libav-user] Why does av_seek_frame() not seek
On Thu, Jul 19, 2012 at 12:42 PM, Carl Eugen Hoyos ceho...@ag.or.at wrote:
[...]
Afair, Reimar believes the seek function should not try hard to find
a keyframe because seeking faster is more important.
I think the current functionality is OK, provided it's documented
well. Though to be honest
On Thu, Jul 19, 2012 at 1:54 PM, Hendrik Leppkes h.lepp...@gmail.com wrote:
[...]
If you want to do accurate seeks with only avformat, you have to add a lot
of boilerplate on top of it right now - or if you want to do accurate seeks
even with ffmpeg. Sure, if you tell it to seek, it'll output
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