[FFmpeg-devel] [Issue 664] [PATCH] Fix AAC PNS Scaling

[Alex Converse]

On Tue, Oct 7, 2008 at 8:55 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Tue, Oct 07, 2008 at 05:23:56PM -0400, Alex Converse wrote:
>> On Tue, Oct 7, 2008 at 5:01 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> > On Tue, Oct 07, 2008 at 04:40:20PM -0400, Alex Converse wrote:
>> >> On Tue, Oct 7, 2008 at 4:27 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> > On Tue, Oct 07, 2008 at 03:23:50PM -0400, Alex Converse wrote:
>> >> >> On Tue, Oct 7, 2008 at 1:01 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> >> > On Mon, Oct 06, 2008 at 11:30:56PM -0400, Alex Converse wrote:
>> >> >> >> On Mon, Oct 6, 2008 at 10:20 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> >> >> > On Mon, Oct 06, 2008 at 09:52:51PM -0400, Alex Converse wrote:
>> >> >> >> >> On Mon, Oct 6, 2008 at 9:39 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> [...]
>> >> >> I'm using the Carmack-Lomont 1/sqrtf based on the following benchmark:
>> >> >>
>> >> >> With math.h sqrtf
>> >> >> alex at Barcelona:~/Projects/ffmpeg/14496-4$ ../ffmpeg/ffmpeg -i
>> >> >> mpeg4audio-conformance/compressedMp4/al18_48.mp4 -f null -
>> >> >> FFmpeg version SVN-r15584, Copyright (c) 2000-2008 Fabrice Bellard, et al.
>> >> >>   configuration: --enable-gpl
>> >> >>   libavutil     49.11. 0 / 49.11. 0
>> >> >>   libavcodec    52. 0. 0 / 52. 0. 0
>> >> >>   libavformat   52.22. 1 / 52.22. 1
>> >> >>   libavdevice   52. 1. 0 / 52. 1. 0
>> >> >>   built on Oct  7 2008 14:26:51, gcc: 4.3.2
>> >> >> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
>> >> >> 'mpeg4audio-conformance/compressedMp4/al18_48.mp4':
>> >> >>   Duration: 00:01:00.01, start: 0.000000, bitrate: 67 kb/s
>> >> >>     Stream #0.0(und): Audio: aac, 48000 Hz, mono, s16
>> >> >> Output #0, null, to 'pipe:':
>> >> >>     Stream #0.0(und): Audio: pcm_s16le, 48000 Hz, mono, s16, 768 kb/s
>> >> >> Stream mapping:
>> >> >>   Stream #0.0 -> #0.0
>> >> >> Press [q] to stop encoding
>> >> >> 253170 dezicycles in sqrtf, 1 runs, 0 skips
>> >> >> 245160 dezicycles in sqrtf, 2 runs, 0 skips
>> >> >> 240997 dezicycles in sqrtf, 4 runs, 0 skips
>> >> >> 238050 dezicycles in sqrtf, 8 runs, 0 skips
>> >> >> 236553 dezicycles in sqrtf, 16 runs, 0 skips
>> >> >> 235676 dezicycles in sqrtf, 32 runs, 0 skips
>> >> >> 234884 dezicycles in sqrtf, 64 runs, 0 skips
>> >> >> 234129 dezicycles in sqrtf, 128 runs, 0 skips
>> >> >> 234115 dezicycles in sqrtf, 256 runs, 0 skips
>> >> >> 234366 dezicycles in sqrtf, 512 runs, 0 skips
>> >> >> 233892 dezicycles in sqrtf, 1024 runs, 0 skips
>> >> >> 233624 dezicycles in sqrtf, 2047 runs, 1 skips
>> >> >> size=      -0kB time=59.99 bitrate=  -0.0kbits/s
>> >> >> video:0kB audio:5624kB global headers:0kB muxing overhead -100.000382%
>> >> >>
>> >> >> With Carmack-Lomont
>> >> >> alex at Barcelona:~/Projects/ffmpeg/14496-4$ ../ffmpeg/ffmpeg -i
>> >> >> mpeg4audio-conformance/compressedMp4/al18_48.mp4 -f null -
>> >> >> FFmpeg version SVN-r15584, Copyright (c) 2000-2008 Fabrice Bellard, et al.
>> >> >>   configuration: --enable-gpl
>> >> >>   libavutil     49.11. 0 / 49.11. 0
>> >> >>   libavcodec    52. 0. 0 / 52. 0. 0
>> >> >>   libavformat   52.22. 1 / 52.22. 1
>> >> >>   libavdevice   52. 1. 0 / 52. 1. 0
>> >> >>   built on Oct  7 2008 14:26:51, gcc: 4.3.2
>> >> >> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
>> >> >> 'mpeg4audio-conformance/compressedMp4/al18_48.mp4':
>> >> >>   Duration: 00:01:00.01, start: 0.000000, bitrate: 67 kb/s
>> >> >>     Stream #0.0(und): Audio: aac, 48000 Hz, mono, s16
>> >> >> Output #0, null, to 'pipe:':
>> >> >>     Stream #0.0(und): Audio: pcm_s16le, 48000 Hz, mono, s16, 768 kb/s
>> >> >> Stream mapping:
>> >> >>   Stream #0.0 -> #0.0
>> >> >> Press [q] to stop encoding
>> >> >> 197190 dezicycles in sqrtf, 1 runs, 0 skips
>> >> >> 190665 dezicycles in sqrtf, 2 runs, 0 skips
>> >> >> 187807 dezicycles in sqrtf, 4 runs, 0 skips
>> >> >> 185737 dezicycles in sqrtf, 8 runs, 0 skips
>> >> >> 184651 dezicycles in sqrtf, 16 runs, 0 skips
>> >> >> 184255 dezicycles in sqrtf, 32 runs, 0 skips
>> >> >> 183868 dezicycles in sqrtf, 64 runs, 0 skips
>> >> >> 183976 dezicycles in sqrtf, 128 runs, 0 skips
>> >> >> 183913 dezicycles in sqrtf, 256 runs, 0 skips
>> >> >> 184199 dezicycles in sqrtf, 511 runs, 1 skips
>> >> >> 184037 dezicycles in sqrtf, 1023 runs, 1 skips
>> >> >> 183925 dezicycles in sqrtf, 2047 runs, 1 skips
>> >> >> size=      -0kB time=59.99 bitrate=  -0.0kbits/s
>> >> >> video:0kB audio:5624kB global headers:0kB muxing overhead -100.000382%
>> >> >>
>> >> >> Intel(R) Core(TM)2 CPU 6600  @ 2.40GHz
>> >> >
>> >> > please try ff_sqrt() as well
>
> [...]
>> Attached is a version that explicitly uses a int32_t.
>
> i will object to this patch until someone posts a speed comparission
> between it and ff_sqrt.
>
> Besides this, you are mis-attributing the code, neither carmack nor
> lomont are the the original authors of it.
> lomont himself attributes the code to carmack, his own modification
> with a different constant isnt used in your patch.
> and carmack denies being the author at
> http://www.beyond3d.com/content/articles/8/
>

I'm sick of arguing with you about this, and I'm sick of being greeted
with hostility when I'll I'm trying to do is fix bugs. I clearly don't
have the stomach for FFMpeg development. Swain or who ever else might
be interested is welcome to takeover this patch. I'm out of here.

Regards,
Alex Converse