[FFmpeg-devel] [PATCH] G.729 Frame erasure support for fixed-codebook vector decoding

[Michael Niedermayer]

On Sat, Jun 27, 2009 at 02:31:40AM +0700, Vladimir Voroshilov wrote:
> subj
[...]
> @@ -224,6 +225,9 @@ static av_cold int decoder_init(AVCodecContext * avctx)
>      ctx->lsp[1] = ctx->lsp_buf[1];
>      memcpy(ctx->lsp[0], lsp_init, 10 * sizeof(int16_t));
>  
> +    /* random seed initialization */
> +    ctx->rand_value = 21845;

the word pointless comes to mind, at least if this is just used for
frame erasure handling


> +
>      return 0;
>  }
>  
> @@ -336,6 +340,15 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
>          /* Round pitch delay to nearest (used everywhere except ff_acelp_interpolate). */
>          pitch_delay_int  = (pitch_delay_3x + 1) / 3;
>  
> +        if (frame_erasure) {
> +            ctx->rand_value = g729_prng(ctx->rand_value);
> +            fc_indexes   = ctx->rand_value & ((1 << format.fc_indexes_bits) - 1);
> +
> +            ctx->rand_value = g729_prng(ctx->rand_value);
> +            pulses_signs = ctx->rand_value & ((1 << format.fc_signs_bits) - 1);
> +        }

a single call to the prng is probably enough also is the & really needed?


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

It is dangerous to be right in matters on which the established authorities
are wrong. -- Voltaire
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