[FFmpeg-devel] [PATCH] G.729 Frame erasure support for LSF decoding

[Vladimir Voroshilov]

2009/6/25 Michael Niedermayer <michaelni at gmx.at>:
> On Wed, Jun 24, 2009 at 08:18:23PM +0700, Vladimir Voroshilov wrote:
>> 2009/6/24 Michael Niedermayer <michaelni at gmx.at>:
>> > On Sat, Jun 20, 2009 at 02:26:59PM +0700, Vladimir Voroshilov wrote:
>> >
>> > [...]
>> >> diff --git ffmpeg-r19218/libavcodec/g729data.h ffmpeg-r19218_v163/libavcodec/g729data.h
>> >> index a70c705..e202331 100644
>> >> --- ffmpeg-r19218/libavcodec/g729data.h
>> >> +++ ffmpeg-r19218_v163/libavcodec/g729data.h
>> >> @@ -275,4 +275,14 @@ static const int16_t cb_ma_predictor_sum[2][10] = { /* (0.15) */
>> >> ? ?{14585, 18333, 19772, 17344, 16426, 16459, 15155, 15220, 16043, 15708}
>> >> ?};
>> >>
>> >> +/**
>> >> + * ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 2^27
>> >> + * ff_g729_cb_ma_predictor_sum_inv[j][i] = ---------------------------------
>> >> + * ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ff_g720_cb_ma_predictor_sum[j][i]
>> >> + */
>> >
>> > my guess would be that this is also not really "="
>> >
>> >
>> > [...]
>> >> - ? ?ma_predictor ? ? = get_bits(&gb, 1);
>> >> - ? ?quantizer_1st ? ?= get_bits(&gb, VQ_1ST_BITS);
>> >> - ? ?quantizer_2nd_lo = get_bits(&gb, VQ_2ND_BITS);
>> >> - ? ?quantizer_2nd_hi = get_bits(&gb, VQ_2ND_BITS);
>> >> +
>> >> + ? ?if(frame_erasure) {
>> >> + ? ? ? ?skip_bits(&gb, 1 + VQ_1ST_BITS + VQ_2ND_BITS + VQ_2ND_BITS);
>> >> +
>> >> + ? ? ? ?lsf_restore_from_previous(ctx->lsfq, ctx->past_quantizer_outputs,
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?ctx->ma_predictor);
>> >> + ? ?} else {
>> >> + ? ? ? ?uint8_t quantizer_1st; ? ?///< first stage vector of quantizer
>> >> + ? ? ? ?uint8_t quantizer_2nd_lo; ///< second stage lower vector of quantizer (size in bits)
>> >> + ? ? ? ?uint8_t quantizer_2nd_hi; ///< second stage higher vector of quantizer (size in bits)
>> >> +
>> >> + ? ? ? ?ctx->ma_predictor = get_bits(&gb, 1);
>> >> + ? ? ? ?quantizer_1st ? ? = get_bits(&gb, VQ_1ST_BITS);
>> >> + ? ? ? ?quantizer_2nd_lo ?= get_bits(&gb, VQ_2ND_BITS);
>> >> + ? ? ? ?quantizer_2nd_hi ?= get_bits(&gb, VQ_2ND_BITS);
>> >>
>> >
>> > reindent besides i dont like the change, its useless to replace them
>> > by skip
>>
>> I though this version is more clean due to localized usage of variables.
>> It also shows that in erasure case reading of quantizer values is not used.
>>
>> here is my early version without skip, but with two variables per MA
>> predictor (current/prev values).
>
> [...]
>
>> @@ -162,6 +164,27 @@ static void lsf_decode(int16_t* lsfq, int16_t* past_quantizer_outputs[MA_NP + 1]
>> ? ? ?ff_acelp_reorder_lsf(lsfq, LSFQ_DIFF_MIN, LSFQ_MIN, LSFQ_MAX, 10);
>> ?}
>>
>> +static void lsf_restore_from_previous(int16_t* lsfq,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int16_t* past_quantizer_outputs[MA_NP + 1],
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?int ma_predictor_prev)
>> +{
>> + ? ?int16_t* quantizer_output = past_quantizer_outputs[MA_NP];
>> + ? ?int i,k;
>> +
>> + ? ?for (i = 0; i < 10; i++) {
>> + ? ? ? ?int tmp = lsfq[i] << 15;
>> +
>> + ? ? ? ?for (k = 0; k < MA_NP; k++)
>> + ? ? ? ? ? ?tmp -= past_quantizer_outputs[k][i] * cb_ma_predictor[ma_predictor_prev][k][i];
>> +
>> + ? ? ? ?quantizer_output[i] = ((tmp >> 15) * cb_ma_predictor_sum_inv[ma_predictor_prev][i]) >> 12;
>> + ? ?}
>> +
>> + ? ?/* Rotate past_quantizer_outputs. */
>> + ? ?memmove(past_quantizer_outputs + 1, past_quantizer_outputs, MA_NP * sizeof(int16_t*));
>> + ? ?past_quantizer_outputs[0] = quantizer_output;
>> +}
>
> this code is duplicated

Fixed.


-- 
Regards,
Vladimir Voroshilov     mailto:voroshil at gmail.com
JID: voroshil at gmail.com, voroshil at jabber.ru
ICQ: 95587719
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