[Libav-user] Does the image2 demuxer work with a custom AVIOContext?

Robert Krüger krueger at lesspain.de
Thu Feb 20 09:33:19 CET 2014

On Wed, Feb 19, 2014 at 10:02 PM, Paul B Mahol <onemda at gmail.com> wrote:
> On 2/19/14, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
>> Carl Eugen Hoyos <cehoyos at ...> writes:
>>> Robert Krueger <krueger <at> ...> writes:
>>> > cat ~/samples/fate/dpx/lighthouse_rgb48.dpx | ./ffmpeg
>>> > -f image2pipe -vcodec dpx -i - ~/tmp/fromdpx_pipe2.png
>>> > [dpx  <at>  0x7fcb21822600] Overread buffer. Invalid header?
>>> The image is cut in the middle
>> Iiuc, the parser reads the file size from the file
>> header while the decoder calculates the (minimal
>> possible) file size. The value that the parser
>> reads from the file header is too small.
>> I suspect the bug can be fixed by reusing the logic
>> to determine the image size also in the parser or
>> by ignoring the file size outputting everything until
>> the next magic marker.
> There is no bug in parser, bug is in dpx file which do not
> conform to the specification.
> FFmpeg dpx encoder is fine.
> ImageMagick sucks.

OK, I didn't know the file was generated using ImageMagick but I see
it now. Then it is irrelevant for me and I will ignore this as long as
valid dpx files work with this approach. Thank you for the analysis. I
don't know what the sample is used for in fate but maybe it's there
for testing broken dpx files. It just happend to be there when I was
looking for a dpx file to test the image2pipe approach.

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