[FFmpeg-devel] Sample: MPO file format for stereoscopic photos

[Reimar Döffinger]

On Sat, Dec 31, 2011 at 04:48:22PM +0000, Paul B Mahol wrote:
> On 12/31/11, Reimar Doeffinger <Reimar.Doeffinger at gmx.de> wrote:
> > On Sat, Dec 31, 2011 at 03:49:10PM +0000, Paul B Mahol wrote:
> >> On 12/31/11, Reimar Doeffinger <Reimar.Doeffinger at gmx.de> wrote:
> >> > On Sat, Dec 31, 2011 at 10:41:53AM +0000, Paul B Mahol wrote:
> >> >> On 11/17/11, Michael Niedermayer <michaelni at gmx.at> wrote:
> >> >> > On Wed, Nov 16, 2011 at 09:48:31PM +0100, Martin Lambers wrote:
> >> >> >> Hi,
> >> >> >>
> >> >> >> as per a request made here:
> >> >> >> <http://savannah.nongnu.org/bugs/?33366>, I
> >> >> >> uploaded a sample MPO file with the name stereoscopic_photo.mpo
> >> >> >> (info
> >> >> >> text: stereoscopic_photo.txt).
> >> >> >>
> >> >> >> The MPO file format is used by the Fujifilm FinePix Real 3D camera
> >> >> >> (and
> >> >> >> others) to store stereoscopic photo pairs. It basically contains two
> >> >> >> JPEG images, left and right view. Some image readers (but not
> >> >> >> FFmpeg)
> >> >> >> treat MPO files as single-image JPEG files and show the left image
> >> >> >> only.
> >> >> >
> >> >> > support added, we decode both frames one after the other now.
> >> >>
> >> >> Please revert that "support".
> >> >
> >> > Could you please say why? Without that it's at very least a somewhat
> >> > impolite request.
> >>
> >> Isn't this obvious? mpo format is unrelated to mjpeg. Feel free to
> >> write demuxer.
> >
> > Uh, looking at the patch the MPO format _is_ MJPEG so I have no idea why
> > you'd call it "unrelated"?!?
> 
> Look at MPO format specifications posted by OP.

I did. The file format is MJPEG, though with some extra information
(index etc.) in APP data.
Most of the extra data seems most appropriate to process on an
application level, not the demuxer level.
And I don't see much if any value in the index really.
So I don't see what you problem with it is that you'd rather not have it
"supported" at all?
Considering it is only an extension mapping it is somewhat useless, but
I am trying to add some content-based detection for image formats and a
separate demuxer would cause additional pain for no benefit I can see.