帧率ffmepg 摄像头,使用ffmpeg获取帧数

古城微笑少年丶 2022-10-04 12:54 299阅读 0赞

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Does anyone know how to fetch the number of total frames from a video file using ffmpeg? The render output of ffmpeg shows the current frame and I need the frame count to calculate the progress in percent.

解决方案

Note: The presence of an edit list in MP4/M4V/M4A/MOV can affect your frame number. See Edit lists below.

ffprobe: Query the container

ffprobe -v error -select\_streams v:0 -show\_entries stream=nb\_frames -of default=nokey=1:noprint\_wrappers=1 input.mp4

This is a fast method.

Not all formats (such as Matroska) will report the number of frames resulting in the output of N/A. See the other methods listed below.

ffprobe: Count the number of frames

ffprobe -v error -count\_frames -select\_streams v:0 -show\_entries stream=nb\_read\_frames -of default=nokey=1:noprint\_wrappers=1 input.mkv

This is a slow method.

Add the -skip\_frame nokey option to only count key frames.

ffmpeg: Count the number of frames

If you do not have ffprobe you can use ffmpeg instead:

ffmpeg -i input.mkv -map 0:v:0 -c copy -f null -

This is a somewhat fast method.

Refer to frame= near the end of the console output.

Add the -discard nokey input option (before -i) to only count key frames.

Edit lists

Ignore the MP4/M4V/M4A/MOV edit list with the -ignore\_editlist 1 input option. Default is to not ignore the edit list.

What the ffprobe options mean

\-v error This hides "info" output (version info, etc) which makes parsing easier.

\-count\_frames Count the number of frames per stream and report it in the corresponding stream section.

\-select\_streams v:0 Select only the video stream.

\-show\_entries stream=nb\_frames or -show\_entries stream=nb\_read\_frames Show only the entry for nb\_frames or nb\_read\_frames.

\-of default=nokey=1:noprint\_wrappers=1 Set output format (aka the "writer") to default, do not print the key of each field (nokey=1), and do not print the section header and footer (noprint\_wrappers=1). There are shorter alternatives such as -of csv=p=0.

Also see

mediainfo

The well known mediainfo tool can output the number of frames:

mediainfo --Output="Video;%FrameCount%" input.avi

MP4Box

For MP4/M4V/M4A files.

MP4Box from gpac can show the number of frames:

MP4Box -info input.mp4

Refer to the Media Info line in the output for the video stream in question:

Media Info: Language "Undetermined (und)" - Type "vide:avc1" - 2525 samples

In this example the video stream has 2525 frames.

boxdumper

For MP4/M4V/M4A/MOV files.

boxdumper is a simple tool from l-smash. It will output a large amount of information. Under the stsz sample size box section refer to sample\_count for the number of frames. In this example the input has 1900 video frames:

boxdumper input.mp4

...

\[stsz: Sample Size Box\]

position = 342641

size = 7620

version = 0

flags = 0x000000

sample\_size = 0 (variable)

sample\_count = 1900

Be aware that a file may have more than one stsz atom.

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