HEVC (High Efficiency Video Coding) is a popular video compression standard that allows for better video quality at lower bitrates. NVENC is a hardware encoder used by NVIDIA GPUs to accelerate video encoding. When encoding videos using NVENC, it is important to ensure that the colorspace is preserved accurately to avoid any loss in quality.
By default, NVENC encodes videos using the YUV colorspace, which is a widely used colorspace for video encoding. However, if you want to preserve the colorspace of your original video without any loss, you may need to use the hwdownload option.
The hwdownload option allows you to retrieve the encoded video data from the GPU memory and save it to a file. This file can then be used as an input for further processing or encoding. By using this option, you can ensure that the colorspace is preserved accurately during the encoding process.
Here is an example command to perform a lossless colorspace HEVC NVENC encoding with the hwdownload option:
ffmpeg -hwaccel cuvid -c:v h264_cuvid -i input.mp4 -c:v hevc_nvenc -rc:v vbr_hq -cq:v 19 -pixel_format yuv444p -flags +ildct+ilme+low_delay -bf 0 -hwdownload output.yuv
In the above command, we are using the FFmpeg tool to encode a video using NVENC. The input.mp4 is the input video file, and output.yuv is the output file where the encoded video data will be saved.
The -pixel_format option is set to yuv444p to ensure that the colorspace is preserved accurately. The -flags option is used to enable certain encoding flags that help in preserving the colorspace. The -hwdownload option is used to save the encoded video data to the output file.
Once you have the encoded video data saved to the output file, you can use it as an input for further processing or encoding. For example, you can use FFmpeg to convert the encoded video data to a different format or perform any other desired operations.
It is worth noting that using the hwdownload option may have some performance implications, as it involves retrieving the video data from the GPU memory. Therefore, it is recommended to use it only when preserving the colorspace accurately is crucial for your specific use case.
References
| Reference | Link |
|---|---|
| HEVC (High Efficiency Video Coding) | https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding |
| NVENC | https://developer.nvidia.com/video-encode-decode-gpu-support-matrix |
| FFmpeg | https://ffmpeg.org/ |