[FFmpeg-user] essence MD5 for still images

Carl Eugen Hoyos ceffmpeg at gmail.com
Wed Jan 10 03:31:22 EET 2018

2018-01-09 22:25 GMT+01:00 *** <gli7676 at gmail.com>:
> On the same subject

Appears to be a different subject, but most of all, please
remember not to top-post on this mailing list.

> when calculating the MD5 of an audio WAV file ffmpeg
> defaults to 16 bit.

No, ffmpeg does not default to "16 bit" or a particular
encoder, some muxers default to pcm_s16le for audio
if you do not specify a particular encoder.

> If the input is 24 bit it is my understanding that
> it needs to be explicitly reflected in the command
> as -c:a pcm_s24le otherwise the resulting MD5 will
> not be accurate.

So, yes, if you need accurate md5 for 24 bit input,
you have to specify a 24 bit encoder.

> Are there comparable variations in the way ffmpeg
> processes still image files of different formats, bit
> depths, etc., that need to be accounted for in the
> command that is used?

Typically not:
The rawvideo (and the wrapped_avframe) encoder
accepts any pix_fmt while the pcm_s16le encoder
only accepts s16 input, the pcm_s24le encoder only
supports s32 (sic!).

Carl Eugen

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