[FFmpeg-devel] [PATCH] AAC: type puns for 16 bit floating point rounding

[Alex Converse]

On Tue, Dec 9, 2008 at 5:58 PM, Robert Swain <robert.swain at gmail.com> wrote:

> 2008/12/9 Guillaume POIRIER <poirierg at gmail.com>:
> > Hello,
> >
> > On Tue, Dec 9, 2008 at 7:27 PM, Robert Swain <robert.swain at gmail.com>
> wrote:
> >> 2008/12/9 Guillaume POIRIER <poirierg at gmail.com>:
> >> Grab:
> >>
> http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_IEC_14496-4_2004_Conformance_Testing/audio_conformance/mpeg4audio-conformance/compressedMp4/am01_48.mp4
> >>
> >> or some other am* file from there, though not am02* as there's a known
> >> bug with those at the moment.
> >
> > These samples are too short, so I'm afraid that I'm measuring ffmpeg's
> > startup time rather than AAC decoding (it takes about .2 seconds to
> > decode the file, from launch of FFmpeg to exit).
> >
> > Would it work with any iTunes-encoded AAC file? If not, maybe you
> > should direct me to a bigger sample from Mplayer's samples
> > collections...
>
> It needs to be an AAC Main profile file. iTunes files are LC AAC as
> are most other AAC streams in the wild. If I find a longer sample,
> I'll let you know. In the mean time, thanks for trying. :)
>

A longer sample can be made with mp4box as follows.

mp4box -raw 1 am00_48.mp4
cat am00_48_track1.aac am00_48_track1.aac (...) > out.aac
mp4box -add out.aac out.mp4

--Alex