Re: [FFmpeg-user] Frame rates and video accelerated
Werner Robitza gmail.com> writes: > On Mon, Feb 9, 2015 at 9:10 PM, elmaxsrl.it> wrote: > > I'm pretty sure that the raw H264 hasn't the timestamps. > > The NAL units themselves, no, but AFAIK the SPS > can indicate the time base according to the VUI > information in Annex E of H.264. FFmpeg unfortunately does not always read these timestamps correctly... Carl Eugen ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Frame rates and video accelerated
On Mon, Feb 9, 2015 at 9:10 PM, wrote: >I'm pretty sure that the raw H264 hasn't the timestamps. The NAL units themselves, no, but AFAIK the SPS can indicate the time base according to the VUI information in Annex E of H.264. So you have to make sure that this is present for ffmpeg to detect it. >Then I prepare the command to launch by sw the FFMPEG: > ffmpeg -y -i IMAGE_FILE.h264 -vf scale=960:-1 -c:v mpeg4 -q:v 1 > IMAGE_FILE.mp4 > ... >Stream #0:0: Video: h264 (Baseline), yuv420p, 1280x720, 25 fps, 25 > tbr, 1200k tbn, 50 tbc It assumes 25 fps here. Like I said, try "-r 12.5" or whatever you need, e.g. ffmpeg -r 12.5 -i input output (Please do not top-post on this mailing list. Thanks!) ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Frame rates and video accelerated
Dear Sir,
Yes, is Annex B compliant.
I take the raw H264 from camera. In this example is a Sony IPELA.
Below the code that receives the raw data from the camera, via RTSP (as I
said I use Live555):
unsigned int num = 0;
shared_ptr > imageNAL = make_shared >();
char const* sPropPar = _fSubsession.fmtp_spropparametersets();
if(sPropPar == nullptr || strlen(sPropPar) == 0)
envir()<<"\n***spropparameterssteds NULL***\n";
SPropRecord *sps = parseSPropParameterSets(sPropPar, num);
for(register unsigned k = 0; k < num; ++k) {
if(sps[k].sPropLength == 0) {
envir()<<"\n***SPS NULL***\n";
continue;
}
unsigned nalUnitSize = sps[k].sPropLength;
unsigned char* nalUnitBytes = sps[k].sPropBytes;
//write the SPS & PPS
imageNAL->push_back(0x00);
imageNAL->push_back(0x00);
imageNAL->push_back(0x00);
imageNAL->push_back(0x01);
for(register unsigned i = 0; i < nalUnitSize; i++) {
imageNAL->push_back(static_cast(nalUnitBytes[i]));
}
//#define DEBUG_PPS
/*#ifdef DEBUG_PPS
std::cout<size(); index++) {
std::cout<(imageNAL->at(index)) & 0xFF)<<" ";
}
std::cout<push_back(0x00);
imageNAL->push_back(0x00);
imageNAL->push_back(0x00);
imageNAL->push_back(0x01);
if(frameSize >= DUMMY_SINK_RECEIVE_BUFFER_SIZE_H264) {
frameSize = DUMMY_SINK_RECEIVE_BUFFER_SIZE_H264-1;
envir()<<"\n***Discard bytes exceed framesize***\n";
}
for(register unsigned i = 0; i < frameSize; i++) {
imageNAL->push_back(_fReceiveBuffer[i]);
}
I save the H264 taken in a file. I take about 10 sec. when an intrution is
detected.
I'm pretty sure that the raw H264 hasn't the timestamps.
Then I prepare the command to launch by sw the FFMPEG:
ffmpeg -y -i IMAGE_FILE.h264 -vf scale=960:-1 -c:v mpeg4 -q:v 1
IMAGE_FILE.mp4
the result is:
Â
ffmpeg version N-66745-g0578623 Copyright (c) 2000-2014 the FFmpeg developers
built on Oct 9 2014 02:15:39 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
configuration: --prefix=HOME/ffmpeg_build --bindir=/home/cchieppa/bin
libavutil 54. 10.100 / 54. 10.100
libavcodec 56. 4.101 / 56. 4.101
libavformat56. 9.100 / 56. 9.100
libavdevice56. 1.100 / 56. 1.100
libavfilter 5. 1.103 / 5. 1.103
libswscale 3. 1.100 / 3. 1.100
libswresample 1. 1.100 / 1. 1.100
Input #0, h264, from '/home/cchieppa/Documents/VideoHUB5/image_SONY.h264':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: h264 (Baseline), yuv420p, 1280x720, 25 fps, 25 tbr,
1200k tbn, 50 tbc
Output #0, mp4, to '/home/cchieppa/Documents/VideoHUB5/image_SONY.mp4':
Metadata:
encoder : Lavf56.9.100
Stream #0:0: Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 960x540,
q=2-31, 200 kb/s, 25 fps, 12800 tbn, 25 tbc
Metadata:
encoder : Lavc56.4.101 mpeg4
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
frame= 336 fps= 41 q=1.0 Lsize= 11566kB time=00:00:13.88
bitrate=6826.1kbits/s
video:11563kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 0.020902%
In this case, the MP4 is too fast: I see the seconds on the video that go
around x2 times fast.
I don't understand why.
Thank you
Cristiano
Da ffmpeg-user-boun...@ffmpeg.org
A "FFmpeg user questions" ffmpeg-user@ffmpeg.org
Cc
Data Mon, 9 Feb 2015 19:24:20 +0100
Oggetto Re: [FFmpeg-user] Frame rates and video accelerated
> On Sat, Feb 7, 2015 at 6:05 PM, Cristiano Chieppa
> wrote:
> > I save the raw frames (NALs) in a file (some frames grabbed from a
camera) and I invoke the ffmpeg from the sw - like a batch program - to encode
the raw H264 in MP4.
> > The conversion works well.
>
> Out of curiosity, how exactly are you doing it? Is the file basically
> an Annex B stream?
>
> > Sometimes, under circumstance that I’m not able to understand, I see
that the generated mp4 video is like “accelerated”: the speed is very fast
compare with the real stream.
> > Is there a way to invoke ffmpeg and tell him, as a parameter, the
timestamp of each grabbed frames to get the real synchronized video?
>
> ffmpeg -r 25 -i input output
>
> This is how you force the frame rate.
>
> Actually, when you do "ffmpeg -i input -c:v libx264 output.h264", the
> output file indicates the frame rate when you read it back in
Re: [FFmpeg-user] Frame rates and video accelerated
On Sat, Feb 7, 2015 at 6:05 PM, Cristiano Chieppa wrote: > I save the raw frames (NALs) in a file (some frames grabbed from a camera) > and I invoke the ffmpeg from the sw - like a batch program - to encode the > raw H264 in MP4. > The conversion works well. Out of curiosity, how exactly are you doing it? Is the file basically an Annex B stream? > Sometimes, under circumstance that I’m not able to understand, I see that > the generated mp4 video is like “accelerated”: the speed is very fast compare > with the real stream. > Is there a way to invoke ffmpeg and tell him, as a parameter, the timestamp > of each grabbed frames to get the real synchronized video? ffmpeg -r 25 -i input output This is how you force the frame rate. Actually, when you do "ffmpeg -i input -c:v libx264 output.h264", the output file indicates the frame rate when you read it back in with "ffmpeg -i output.h264". And when you force a different frame rate, with for example "ffmpeg -i input -c:v libx264 -r 12 output.h264", this frame rate change is visible when doing "ffmpeg -i output.h264". This is due to the timing information being written into the Sequence Parameter Set (SPS). ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
[FFmpeg-user] Frame rates and video accelerated
Dear Users, I’m newbie with FFMpeg so, apologize if the question is trivial for you. I’m getting a raw H264 bitstream (in C++) via RTSP from IP camera (really I’m using many models). I haven’t the audio. I save the raw frames (NALs) in a file (some frames grabbed from a camera) and I invoke the ffmpeg from the sw - like a batch program - to encode the raw H264 in MP4. The conversion works well. Sometimes, under circumstance that I’m not able to understand, I see that the generated mp4 video is like “accelerated”: the speed is very fast compare with the real stream. I’m struggling with this behavior and I’m trying to understand why. I tried to find on Google other questions like the mine without find a good answer. If I well understand (please, kindly correct me), raw H264 doesn’t contain the timestamp of the frames: should be responsibility of the container. Furthermore, the streaming from IP camera should not at constant frames per rates, so their duration could be very different (again, please correct me). During the grabbing of the NALs (I’m using Live555) I get the timestamps too from RTP: I save these in another file. Is there a way to invoke ffmpeg and tell him, as a parameter, the timestamp of each grabbed frames to get the real synchronized video? Or, better, does someone met this problem and solved? I’m sure that I wrong something. I’m very confused. Thank you Cristiano ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
