[MEncoder-users] compression: 1080i versus 720p

[Andrew Berg]

On 12/17/2009 9:45 AM, Matyas wrote:
> I have encoded several 1080i and 720p OTA sources.  The only
> difference was that I used deinterlacing for the 1080i and that
> I scaled differently: I scaled the 1080i to 960:540, while the
> 720p to 768:432.  I used crf=23 for both encodes with h.264.
>
> The resulting bitrate for the 1080i sources varied between 1100
> and 1900.  For the 720p sources it was over 2000.  The 720p source
> is more dynamic but I still was surprised to see the much higher
> bitrate on a smaller resolution.
I mostly deal with DVDs, and I've had bitrates as low as ~600kbps (Home
Movies) and as high as ~3500kbps (noisy pro wrestling events, most are
2500-3000kbps) using nearly identical settings (I use a higher ref and
omit the weight_b parameter for animation) with CRF=19. Certain content
like simple animation requires very few bits, while other content like
pro wrestling or action movies requires a lot of bits.
Also, it seems that CRF should be adjusted for different resolutions. I
read that somewhere and a couple tests I did favored that notion, but I
need to do more tests be sure.