[FFmpeg-user] Calculate file size for lossless encoding

[Ulf Zibis]

Am 01.10.23 um 16:37 schrieb Paul B Mahol:
> On 10/1/23, Ulf Zibis <Ulf.Zibis at cosoco.de> wrote:
>> Hi,
>>
>> I used the following command on a 155 minute grabbing:
>>
>> ffmpeg -video_size 1680x888 -framerate 25 -f x11grab -i :0.0+0,81 -c:v
>> libx264rgb -crf 0 -preset ultrafast output.mkv
>>
>> Assuming, the RGB range is 8 + 8 + 8 bit or 3 byte, I calculate:
>>
>> 3 x 25 x 60 x 155 x 1680 x 888 = 1040.6 GByte
>>
>> But the file is only 93.7 GByte.
>>
>> How can that be ?
> Encoder was specified. Lossless encoders can still compress data.

So here it compresses with factor ~11, wow, great performance for ultrafast.

-Ulf