Can you encode intra-frame videos from inter-frame without loss?
An encoder receives and works upon uncompressed frames and does not know or care about the encoding of the source stream.

To avoid any information loss, you have to set lossless mode. For x264, this is by done by adding -qp 0 to your ffmpeg command. But for most purposes, strict mathematical losslessness is not required. See What&#39;s the difference between &quot;visually lossless&quot; and real lossless and what does this mean for future encodes?