Hello,
From my humble experience, you should provide PTS/DTS being incremented
sequentially and
avoid jumping or duplication of PTS/DTS as much as possible. That means the first frame being
recorded should have 0, the next 1 and so on.. (PTS/DTS should be calculated using av_rescale_q..)
In your case you provided 4752 twice and that's why you see such an error
message.
Starting from greater-than-zero may also lead such an error..
Also you should set same value for PTS and DTS before calling
av_interleaved_write_frame..
Regards,
2016-12-29 오전 11:32에 yoann 이(가) 쓴 글:
At 2016-12-27 14:06:14, "yoann" <[email protected]> wrote:
Hi everyone,
I am trying to remux a mp4 RTSP stream (provided by an ffserver) into a mp4
file, but I am
struggling to get the file set correctly. I do not want to re-encode the
stream for performances
reasons.
Using the remuxing.c example, I met different issues :
- if I use the example directly, the PTS and DTS of the firsts frames are
mixed up and
av_write_interleaved_frames gives me a "Application provided invalid, non
monotonically
increasing dts to muxer in stream 0: 4752 >= 4752" error.
- if I skip a random amount of frames (I would also like to be able to
start remuxing from
anywhere in the stream and not only from the start), it produces a file
which is eventually
readable but analyzing it with ffprobe -show_frames, it throws me a
"Missing key frame while
reordering index according to edit list", which is understandable, I need
my first frame to be
an keyframe I think.
- If I try to use AV_PKT_FLAG_KEY to ensure my first frame is a keyframe,
it does not changes
anything, and printing the pkt.flags field give me that almost one frame on
2 i a keyframe,
which is false, it is around 1 on 10 for my RTSP stream. Am I not using
this flag correctly ?
I should have precised that it is a h264 stream. And from what I understood
from this thread
: https://ffmpeg.org/pipermail/libav-user/2013-December/005997.html,
AV_PKT_FLAG_KEY is directly
read from the h264 stream and not set by libavformat and is not the relevant
information, the index
entry is.
So if I want to start the remuxing into a file from any random point, what
would be the easiest way
to ensure I am starting with a keyframe ?
I can try to decode the first few frames and than check AVframe->key_frame but
the performances will
be poor. Is using av_seek_frame here useful is some manner ?
Here is my modified code for remuxing.c :
// same that remuxing.c before, here is around line 130
i = 0;
int have_first_keyframe = 0;
while (1) {
AVStream *in_stream, *out_stream;
ret = av_read_frame(ifmt_ctx, &pkt);
if (ret < 0)
break;
i++;
if(i <= 54){ // random number to start further in the stream
av_packet_unref(&pkt);
continue;
}
fprintf(stderr, "pkt.flags : %d \n", pkt.flags);
if(!have_first_keyframe){
if((pkt.flags & AV_PKT_FLAG_KEY) == 0){
// not a keyframe
av_packet_unref(&pkt);
continue;
} else {
have_first_keyframe = 1;
}
}
// same that remuxing.c after except I use i = 700 to break the loop
and stop remuxing
Here is what the output looks like :
pkt.flags : 0
No keyframe
pkt.flags : 1
First keyframe
pkt.flags : 1
pkt.flags : 0
pkt.flags : 1
pkt.flags : 1
pkt.flags : 0
pkt.flags : 1
pkt.flags : 0
pkt.flags : 1
pkt.flags : 1
pkt.flags : 1
pkt.flags : 0
pkt.flags : 1
pkt.flags : 1
pkt.flags : 0
pkt.flags : 1
pkt.flags : 1
pkt.flags : 0
pkt.flags : 1
Someone has any advice to record an RTSP stream ?
Yoann
_______________________________________________
Libav-user mailing list
[email protected]
http://ffmpeg.org/mailman/listinfo/libav-user
_______________________________________________
Libav-user mailing list
[email protected]
http://ffmpeg.org/mailman/listinfo/libav-user
