How can I use the Ffmpeg to determine the codec header size from a webm (vp9) stream?

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Using the FFmpeg API, you can use FFprobe, a part of FFmpeg made for in-depth multimedia file analysis, to get the codec header size from a WebM (VP9) stream.

Take these actions:

1. Install FFmpeg

Install FFmpeg on your system using the links below:

2. Use FFprobe

  1. This command-line tool, which comes with FFmpeg, provides thorough information on multimedia files. It can be used to check the size of the codec header in a WebM (VP9) stream.
    Here is a command example:

ffprobe -v error -select_streams v:0 -show_entries packet=size -of default=noprint_wrappers=1:nokey=1 your_video.webm

  1. Replace your_video.webm with the path to your WebM file.

  2. -v error: Sets the verbosity level to error to eliminate superfluous details

  3. -select_streams v:0: Chooses the initial video stream.

  4. -show_entries packet=size: Specifies the desire to display packet (frame) sizes within the stream.

  5. -of default=noprint_wrappers=1:nokey=1: Formats the output to exhibit only the packet sizes, excluding extra data.

3. Execute the command

  1. Run the FFprobe command at the terminal or command prompt to carry out the command. It will provide a list of packet sizes, including the size of the codec header.
  2. For instance, the result might look like this:

103, 114, 104, 78, 78, 6, 11, 48, 20, 19, …

The codec header size is represented by the first value in the list.

4. Get the size of the codec header

  1. Use a computer language like JavaScript or Python to retrieve the codec header size programmatically and include it in your code. The particular implementation depends on the language you choose.
  2. You can use the child_process module in JavaScript (Node.js), for instance, to execute the command and handle the output.

const { exec } = require('child_process');

const videoFilePath = 'your_video.webm';

exec(`ffprobe -v error -select_streams v:0 -show_entries packet=size -of default=noprint_wrappers=1:nokey=1 ${videoFilePath}`, (error, stdout, stderr) => {

if (error) {

console.error(`Error: ${error.message}`);

return;

}

const packetSizes = stdout.trim().split(', ');

const codecHeaderSize = parseInt(packetSizes[0], 10);

console.log(`Codec Header Size: ${codecHeaderSize} bytes`);

});

The code can be modified to fit your specific requirements and preferred programming language.

By following these instructions, you can use FFprobe to determine the codec header size of a WebM (VP9) stream and possibly incorporate this feature into your code or apps as necessary.