[FFmpeg-devel] patch for a new H.264 codec

[Tomas Härdin]

Hi

> +void convert_to_annexb(unsigned char * dest, unsigned long
> data_size)
> +{
> +   unsigned char *current = dest;
> +   union 
> +   {
> +      unsigned char by4[4];
> +      uint32_t length;
> +   } union_u32_byte;
> +  
> +   while ((dest + data_size) > (current + 4))
> +   {
> +      if((current[0] == 0) &&
> +         (current[1] == 0) &&
> +         (current[2] == 0) &&
> +         (current[3] == 1))
> +      {
> +         // in case it is already in annex B
> +         break;
> +      }
> +
> +      union_u32_byte.by4[3] = current[0];
> +      union_u32_byte.by4[2] = current[1];
> +      union_u32_byte.by4[1] = current[2];
> +      union_u32_byte.by4[0] = current[3];

This won't work on certain machines. Type punning is also undefined if
memory serves me right, and may not work right in all compilers.
Definitely not recommended. There are macros in FFmpeg for this already
(AV_RL32 and friends)

> +#ifdef _WIN32
> +   lib_handle = dlopen("mvM264Ffmpeg.dll", RTLD_LAZY);
> +#else   
> +   lib_handle = dlopen("libmvM264Ffmpeg.so", RTLD_LAZY);
> +#endif

I believe FFmpeg has policy specifically against stuff like this. Link
the dynamic library properly, and put appropriate license stuff in
configure. The resulting ffmpeg binaries will more than likely not be
redistributable, libav* might also be depending on what the Matrox
library's license is.

> +   printf("m264_encode_init_h264: avctx->width = %d\n", avctx->width);
> +   printf("m264_encode_init_h264: avctx->height = %d\n", avctx->height);
> +   printf("m264_encode_init_h264: avctx->framerate.num = %d\n", avctx->framerate.num);
> +   printf("m264_encode_init_h264: avctx->framerate.den = %d\n", avctx->framerate.den);
> +   printf("m264_encode_init_h264: avctx->gop_size = %d\n", avctx->gop_size);
> +   printf("m264_encode_init_h264: avctx->bit_rate = %" PRId64 "\n", avctx->bit_rate);

Forgotten debug stuff? printf() is definitely not OK

There are other issues with this patch, but there's no point in looking
more for now

/Tomas