[FFmpeg-user] A question on -tag:v and CPU usage

Ted Park kumowoon1025 at gmail.com
Wed Oct 30 04:40:13 EET 2019

> Does it write the video codec tag per frame, etc?
Not even, It’s per sample, iirc, but
> I ask because I'm seeing some truly abnormal results with hevc_nvenc when
> the -tag:v hvc1 option is passed where the CPU load spikes up significantly.
hvc1 is the one with codec params in the sample description box, so I guess it’s parsing (basically decoding, as I’ve been told) the stream to copy it to the header. (Or box, I should say, rather. And I’m not sure if it also deletes them after, but I’m pretty sure there’s a separate bsf that does that though.)

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