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

Paul B Mahol onemda at gmail.com
Thu Feb 20 15:01:19 CET 2014

On 2/20/14, Robert Krueger <krueger at lesspain.de> wrote:
> 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.

The sample is made before dpx encoder existed in ffmpeg....

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