[NUT-devel] NUT?

[Oded Shimon]

On Sun, Nov 05, 2006 at 06:31:32PM -0800, Ralph Giles wrote:
> On Mon, Nov 06, 2006 at 01:56:53AM +0100, Michael Niedermayer wrote:
> 
> > thats ~ 20 bytes per frame overhead or ~ 0.11%
> > with 15k frames it would have been ~ 11 or ~ 0.07%
> > with 2mb frames you would end up with ~ 22 byte or ~ 0.001%
> 
> Thanks, Michael. Could you do a similar sketch for vorbis audio? I tried 
> nutmerge on a couple of files and it reported 1.2-1.5% overhead, and 
> was curious if the claimed 2 bytes per frame is possible with vorbis.

If you modify nutmerge.c, there's a table at the top, you need to change 
it to this:

frame_table_input_t ft_default[] = {
        // There must be atleast this safety net:
        //{ 4128,      3,   0,   1,      0,    0,     0 },
        //{ flag, fields, pts, mul, stream, size, count }

          { 8192,      0,   0,   1,      0,    0,     0 }, // invalid 0x00
          {   56,      0,   0,   1,      0,    0,     0 }, // safety net non key frame
          {   56,      0,   0,   1,      0,    0,     0 }, // safety net key frame
          { 4128,      0,   0,   1,      0,    0,     0 }, // one more safety net
          {   27,      0,   0,   1,      0,    0,     0 }, // EOR frame
          { 1, 4, 16, 386, 0, 190, 0 },
          { 1, 4,  2,  90, 0,  40, 0 },
          { 32|1, 3,  9,   1, 0,   0, 0 },
          { 32|1, 3, 23,   1, 0,   0, 0 },
          { 32|1, 3,  2,   1, 0,   0, 0 },
          { 8192,      2,   0,   1,      0,    0,     0 }, // invalid 0xFF
          {   -1,      0,   0,   0,      0,    0,     0 }, // end
};


With this, trying 2 samples I have, I got this overhead:

Stream 0:
   frames: 13156
   TOT: packet size: 2764411 packet overhead: 15660 (0.57%)
   AVG: packet size: 210.13 packet overhead: 1.19
Syncpoints: 86 size: 1536
TOTAL: 2764411 bytes data, 29609 bytes overhead, 1.07% overhead

Stream 0:
   frames: 122493
   TOT: packet size: 20807068 packet overhead: 148978 (0.72%)
   AVG: packet size: 169.86 packet overhead: 1.22
Syncpoints: 643 size: 11564
TOTAL: 20807068 bytes data, 175184 bytes overhead, 0.84% overhead



BTW, note that in the former, ~30% of the overhead is the header 
repetition :) (3 header copies, each 4kb big because of vorbis)

- ods15