5
votes
Accepted
Call FFmpeg filter from source code (C API)
You can't just call a filter, You must instantiate a filter graph.
First you need to create a buffer and buffersink via:
AVFilterContext* source = 0;
AVFilterContext* sink = 0;
AVFilterGraph *graph =...
- 1,060
4
votes
How to extract each video scene with FFmpeg
Using the encoder's scenecut to detect scenes is not advisable, since its purpose is efficient GOP splitting taking into account other encoding parameters. It is not a "pure" scene detector. Its ...
- 32.3k
3
votes
Accepted
Print to file: Details of every NAL unit in raw H.264 file
You can use the trace_headers bitstream filter in ffmpeg
ffmpeg -i in.264 -c copy -bsf:v trace_headers -f null - 2> NALUS.txt
The text file will have data like this,
[AVBSFContext @ ...
- 32.3k
3
votes
Accepted
hardware cuda decoding error
Stream 0 is Stream #0:0[0x1006]: Video: mpeg2video for which you need -c:v mpeg2_cuvid
- 32.3k
2
votes
Accepted
Please Explain the Codecs in my Example
So codecs compress and decompress videos, right?
COmpress DECompress. Yep. Just like with text encoding, e.g. ascii or unicode, but with video you take a raster (grid of pixels) and turn that into a ...
- 13.6k
2
votes
Accepted
FFMPEG 4.0 skipping frames
Y4M has no timestamps, only framerate in its header. So, if your source has any variability in its framerate, you'll see a shift in apparent timestamp in the Y4M.
e.g.
n src y4m
0 0 ...
- 32.3k
2
votes
Accepted
Retrieve and decode V-Chip data from an aired digital TV stream
V-Chip is encoded in the Extended Data Services (XDS) that is part EIA-608 captions. How it is actually transported in/with the video depends the signal type and medium.
Analog: Encoded with the ...
- 2,405
1
vote
Accepted
What happens when a compressed video is played back?
In most common compression schemes, there isn't a 1::1 correspondence between "video" frames and "file" (or stream) frames **. Any particular video frame may require the contents of several file ...
- 4,674
1
vote
Accepted
Parallel throughput of Intel QuickSync (QSV) for real time streams
It depends on a lot of factors, but mainly the codec, bitrate and resolution of the source and output files. Unfortunately, I don't know of any websites that catalog the performance of quicksync, but ...
- 93
1
vote
What actually happens to footage that is upscaled or downscaled?
... Depends...
There are many concepts that need to be differentiated. Let me explore a bit.
Information
The first one is that we need to think about an image as information. So we need to ask first. ...
- 1,152
1
vote
Why doesn't FFMPEG output frames as jpg? How can I fix my code?
Your build doesn't have the image2 muxer enabled, which is required for image sequences.
- 32.3k
1
vote
Accepted
Efficient decoding of 10-bit 4k h264 from GH5S?
Nvdec and qsv do not have support for 10 bit AVC. And if there was a more “efficient” software decoder available, it would already be in ffmpeg.
- 1,060
1
vote
How to extract each video scene with FFmpeg
This script makes it simple, better results than other posts around town:
https://gist.github.com/achesco/4dc2ebf13378a0a61fc26c7fe01f539e
Splits file.mp4 file to scenes with change more than 0.5 and ...
- 111
1
vote
Good codec for embedded system video decoding
While I haven't implemented this myself I would suspect Google's VP9 (or VP10) to be a good option.
Considering Android phones use an ARM CPU, the codecs and libraries supporting it should be ...
- 153
1
vote
FFmpeg run multiple filters in parallel from C API
Filters cant really run in parallel because they can modify frames, and you can’t modify a frame in two threads at the same time. You can make a copy of the frame and run two filter graphs.
- 1,060
1
vote
Accepted
Compile FFmpeg example code
It does not produce any output file.
After filtering, display_frame() is called, which simply outputs to the console.
/* Trivial ASCII grayscale display. */
p0 = frame->data[0];
puts("\033c");
...
- 32.3k
1
vote
Objective video quality assessment
What you are looking for is called “no-reference quality assessment”. Google can give you specific examples.
- 1,060
1
vote
Accepted
FFmpeg. CUDA decode. Past duration too large. Variable FPS
The key -drop_second_field 1 fixed this issue. And result command looks as follow:
ffmpeg -y -hwaccel cuvid -c:v h264_cuvid -deint 2 -drop_second_field 1
-i "udp://IP:PORT" -vcodec h264_nvenc -...
- 411
1
vote
hardware cuda decoding error
It's a bug in ffmpeg. When you explicitly specify a type of the HW acceleration (i.e. cuvid), ffmpeg assigns 0 to CUVIDDECODECREATEINFO::ulNumDecodeSurfaces and to CUVIDDECODECREATEINFO::...
- 111
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