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

[Michael Niedermayer]

On Mon, Jun 29, 2009 at 04:32:51AM +0700, Vladimir Voroshilov wrote:
[...]
> >> >> +
> >> >> ? ? ?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?
> >>
> >> As i said before, seed initialization as long as double call to
> >> g729_prng and "&" are defined
> >> in main body of G.729, part 4.4.4 "Generation of the replacement
> >> excitation". Is this
> >> enough reason ?to keep them ?
> >
> > no, its illogic for the handling of damaged frames to require specific bits
> > of a specific PRNG to be used
> > that said, are the & needed or not?
[...]
> P.S. "&" applied to pulse_signs can be safely removed, since extra
> bits are just ignored.

good

[...]
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