[FFmpeg-user] Probing jpg, png and tiff images without decoding frames

Carl Eugen Hoyos cehoyos at ag.or.at
Tue Aug 6 13:23:33 CEST 2013

Robert Krüger <krueger <at> lesspain.de> writes:

> it seems the ffmpeg always decodes the listed 
> types of images to determine their properties.

In your email's subject, you used the term "probing" 
which is defined for FFmpeg / libavformat.
For all listed image formats, FFmpeg does no probing, 
it guesses the format reading the file suffix.
(Something FFmpeg does not do for nearly all formats 
it supports.)

> What I did to check this, was to run
> ffmpeg -i <imagefile> as well as 
> ffprobe -show_streams <imagefile> with each of 
> these formats and set a breakpoint in
> avcodec_decode_video2.

I don't think it is generally possible to find out 
properties of image files (that is apparently what 
you need) without calling this function.

Carl Eugen

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