FFmpeg: VP9 HDR10 4k Input to HEVC Output Not Saving

Introduction

In this article, we will discuss how to encode a 4k VP9 HDR10 video using the command line tool FFmpeg. We will cover the input and output formats, as well as some key concepts related to subtitles and codecs. By the end of this article, you will have a solid understanding of how to use FFmpeg to encode VP9 HDR10 videos.

Input and Output Formats

The input video in this example is in 4k resolution and uses the VP9 codec with HDR10 metadata. The output format will also be VP9, but with additional options to ensure that the HDR10 metadata is preserved.

To encode the video, we will use the following command:

This command uses the VP9 codec with the cuvid hardware acceleration library to encode the video. The -crf option sets the Constant Rate Factor, which controls the trade-off between encoding speed and output quality. A lower CRF value will result in a higher quality output, but will take longer to encode.

The -pass option is used to perform a two-pass encoding, which can improve the encoding efficiency and output quality. In the first pass, FFmpeg analyzes the input video to determine the optimal encoding parameters. In the second pass, FFmpeg uses these parameters to encode the video.

The -c:a copy option is used to copy the audio stream from the input video to the output video without re-encoding. This can save time and preserve the audio quality.

The -c:s copy option is used to copy the subtitle stream from the input video to the output video without re-encoding. This can save time and preserve the subtitle quality.

Key Concepts

Here are some key concepts related to FFmpeg and video encoding:

• Codecs: Codecs are used to encode and decode video and audio data. FFmpeg supports a wide variety of codecs, including VP9, H.264, and H.265.
• Containers: Containers are used to store video, audio, and subtitle data in a single file. Common container formats include MP4, Matroska, and AVI.
• Bitrate: Bitrate is the amount of data used to encode a video or audio stream per second. A higher bitrate will result in a higher quality output, but will also result in a larger file size.
• Constant Rate Factor (CRF): CRF is a value used to control the trade-off between encoding speed and output quality. A lower CRF value will result in a higher quality output, but will take longer to encode.
• Two-pass encoding: Two-pass encoding is a technique used to improve the encoding efficiency and output quality. In the first pass, FFmpeg analyzes the input video to determine the optimal encoding parameters. In the second pass, FFmpeg uses these parameters to encode the video.

Subtitles

FFmpeg supports a wide variety of subtitle formats, including SRT, ASS, and SSA. To include subtitles in the output video, you can use the -c:s option followed by the subtitle codec. For example:

This command will encode the video using the VP9 codec and copy the audio and subtitle streams from the input video to the output video. The subtitle stream will be encoded using the SRT format.

FFmpeg is a powerful command line tool that can be used to encode video and audio files. In this article, we have discussed how to use FFmpeg to encode a 4k VP9 HDR10 video using the command line. We have covered the input and output formats, as well as some key concepts related to subtitles and codecs. With this knowledge, you should be able to use FFmpeg to encode your own VP9 HDR10 videos.

References

• FFmpeg website
• FFmpeg QuickSync documentation
• FFmpeg VAAPI documentation
• FFmpeg CUVID documentation