[FFmpeg-devel] calculation of probe score

Michael Niedermayer michael at niedermayer.cc
Tue Sep 13 13:18:43 EEST 2016


On Mon, Sep 12, 2016 at 12:47:40PM -0500, Monique Lassere wrote:
> Hi, all,
> 
> Trying to dig as deeply as possible into ffprobe's probe score and how it
> is calculated. AVProbeData

> <https://www.ffmpeg.org/doxygen/2.2/structAVProbeData.html> contains a lot

This is the doxy for 2.2 not the latest FFmpeg


> of specific information about the tags and signatures ffprobe uses to
> identify various formats. However, I have noticed some issues that
> AVProbeData does not seem to address (in my novice ability to read C):
> 

> 1. Even if ffprobe does not find a codec ID for a given stream, it can
> still attempt to identify the stream. What type of information does ffprobe
> use to guess the stream?

The information provided by the specific demuxer


> 
> 2. Secondly, does the probe score relate to the container format only? From

yes unless i misunderstand your question


> my look at AVProbeData and the test results I've gotten, that's what it
> looks like: an example is a report from a Matroska file with an identified
> H.264 encoding (lacking an identifiable tag) achieving a score of 100, and
> many others. Therefore, it seems like ffprobe only returns a lower probe
> score if data is missing from the container format.
> 
> Thanks for any thoughts or input.
> 
> Best,
> 
> Monique Lassere
> 
> M.S. Candidate in Library & Information Science, UIUC
> Graduate Assistant at Research & Information Services
> Graduate Hourly at the Rare Book & Manuscript Library
> Format Registry Manager at Digital Bedrock
> LinkedIn <https://www.linkedin.com/in/moniquelassere> || 847-361-0047
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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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