[FFmpeg-user] ffmpeg md5 muxer different outputs on ARM and x86

[Paul B Mahol]

On 11/15/13, Nathan of Guardian <nathan at guardianproject.info> wrote:
>
> I am working on a project that using the ffmpeg md5 muxer to ensure that
> video captured on an Android phone has not manipulated between the time
> it was captured, and when it is received on a remote server. To do this,
> we want to use the md5 and framemd5 muxers to hash the actual video
> contents, and not the entire file itself.
>
> I've built the exact same version of ffmpeg (0.11.1) for Android (ARM)
> and my Linux desktop (x86), but when I run the md5 muxer on the exact
> same file (ffmpeg -i foo.mp4 -f md5 -), I receive different md5 hashes.

Because you are computing hash of decoded output and not actual
contest of files.
Decoded output may differ, exp. for audio decoders that use floating point
sample format.

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