Nero AVC:can't encode in certain resolution.

[Valeron]

I've got many anime clips in 704x396 resolution.
I want to kept the 16:9 AR and the same resolution.
But the Nero AVC doesn't promise it.
It only support weight and height that can be divided by 16.
Though I disable resize,but it still automatic slightly resize the frame to 704x384....
Bore...
Or any good ideas?
Thx.

[hhanh]

I think the codec only supports multiple of 16 in width and height.
If you absolutely want to keep the original size, you need to add black borders so that the effective height is unchanged.
AviSynth has an AddBorder function you can use.

I'm not sure it's such a good idea though, since you introduce high frequency edges that are difficult to encode. Do you really care that much about this exact aspect ratio?

--h

[Valeron]

I really care the AR so much.
I think I have to roll back to my WMV9 encode for these clips.
Though it need a bit larger bitarte.

[hhanh]

Even though Recode will resize your picture, it also recomputes the pixel aspect ratio. During display, the original A/R will be kept.

--h

[midnightsun]

^^ is right. See this portion of NeroRecode log:

Source:
Size (720,576)
Display Aspect Ratio (16,9)
Deinterlace disabled
Cropping enabled (0, 0, 0, 0)
Resizing enabled (720,400)
Pixel ratio (80,81)
Bitrate: 1498575 bps

As you see the output resolution is 720x400, that would yield to an aspect ratio of 1.80, but then it says pixel ratio (80,81), meaning that it encoded with rectangular pixels. If you do your math you'll see that:

(9/5)*(80/81)= 16/9, meaning the source display aspect ratio has been preserved :cool:

[SeeMoreDigital]

Hopefully future versions of Recode2 will support Mpeg4/AVC encoding down to 4x4 or 8x8 macro-bocks...

....apparently is allowable in the Mpeg4/AVC specs!



Cheers

[akupenguin]

Recode does support 8x8 partitions: the option is called "macroblock partitions".
(I don't know why they don't support 4x4. Somewhere in the beta thread an Ateme person said they couldn't get it to help compression. But 4x4 works in x264, and Fenrir is at Ateme now...)

But even with 8x8 partitions, you still lose some efficiency by encoding at only mod8 resolution. A macroblock is still 16x16, and AFAIK edge emulation only applies the edge of the coded picture, not the cropping rectangle. So motion perpendicular to the frame edge will be hard to code.

[babayaga]

Originally posted by akupenguin
Recode does support 8x8 partitions: the option is called "macroblock partitions".
(I don't know why they don't support 4x4. Somewhere in the beta thread an Ateme person said they couldn't get it to help compression.

Subpartitions (4x4, 8x4 and 4x8) do not provide enough coding efficiency in a tool like Recode in regards of the encoding speed penalty.
That's why there is no specific seach for those modes.

Resolution limitations is more an integration issue between the encoder, the decoder, the renderer and the GUI than a technical problem.
This is currently studied for a next release.