[FFmpeg-devel] [PATCH v2 4/5] avformat/chromaprint: Fix writing raw fingerprint

[Andriy Gelman]

On Sun, 06. Oct 01:49, Andriy Gelman wrote:
> From: Andriy Gelman <andriy.gelman at gmail.com>
> 
> The pointer fp after the call to chromaprint_get_raw_fingerpoint() points to an array of uint32_t whereas the current code assumed just a char stream. Thus when writing the raw fingerprint, the output would be truncated by a factor of 4. This is fixed in the commit.
> 
> For reference the declaration of the function from chromaprint.h is:
> int chromaprint_get_raw_fingerprint(ChromaprintContext *ctx, uint32_t **fingerprint, int *size);
> ---
>  libavformat/chromaprint.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavformat/chromaprint.c b/libavformat/chromaprint.c
> index a4c0b97d99..faa92ca0db 100644
> --- a/libavformat/chromaprint.c
> +++ b/libavformat/chromaprint.c
> @@ -136,7 +136,7 @@ static int write_trailer(AVFormatContext *s)
>  
>      switch (cpr->fp_format) {
>      case FINGERPRINT_RAW:
> -        avio_write(pb, fp, size);
> +        avio_write(pb, fp, size * 4); //fp points to array of uint32_t
>          break;
>      case FINGERPRINT_COMPRESSED:
>      case FINGERPRINT_BASE64:
> -- 
> 2.23.0

ping 

To reproduce the error, we can compare the results to fpcalc (chromaprint
utility https://acoustid.org/chromaprint) 

$ ffmpeg -f lavfi -i sine=d=4 -f s16le testsample.raw 
$ fpcalc -format s16le -raw -plain testsample.raw
558758263,558758263,558758263,558758263,558758263,558758263,558758263,558758263,558758263,558758263,558758263

#with ffmpeg (need to typecast output bytesteam to uint32 to compare) 
$ ffmpeg -f lavfi -i sine=d=4 -f s16le -f chromaprint -fp_format raw fingerprint.raw
$ python3 -c "import numpy; print(numpy.fromfile(\"fingerprint.raw\", dtype=numpy.uint32))" 
[558758263 558758263]

Applying this commit makes the outputs same size

-- 
Andriy