[FFmpeg-devel] [PATCH] avcodec/dcaenc: Initial implementation of ADPCM encoding for DCA encoder

[Даниил Чередник]

Tiny fix: missed inline attr.

On Thu, May 4, 2017 at 1:17 AM, Даниил Чередник <dan.cherednik at gmail.com>
wrote:

> All notices were fixed. Also I found issue with uninitialized subband
> buffer - fixed. New patch attached.
>
> On Wed, May 3, 2017 at 7:49 AM, Rostislav Pehlivanov <atomnuker at gmail.com>
> wrote:
>
>> On 2 May 2017 at 22:53, Даниил Чередник <dan.cherednik at gmail.com> wrote:
>>
>> > Hi.
>> >
>> > This patch introduces initial implementation of subband ADPCM encoding
>> for
>> > DCA codec.
>> >
>> > Some results:
>> >
>> > sample:
>> >
>> > https://yadi.sk/d/B_3sVskM3HZiWK - original
>> >
>> > https://yadi.sk/d/7CK47Nt63HZiWf - without adpcm
>> >
>> > https://yadi.sk/d/25q1JDV93HZiWq - with adpcm
>> >
>> > chirp tone:
>> >
>> > https://yadi.sk/i/tZKHoJ1d3HZk4c
>> >
>> > Right now this feature is disabled by default. But it is ready to try
>> > using -dca_adpcm 1 option.
>> >
>> > There are some issues, should be solved before enabling this feature by
>> > default:
>> >
>> > 1. Speed up: I am trying to find best filter in each subband. But with
>> real
>> > signal, usually only few subbands has significant prediction gain. The
>> idea
>> > is try to analyze FFT spectrum (which is already calculated), to check
>> is
>> > particular subband looks like tonal or noise. If subband is noise like
>> - do
>> > not try to find best LPC predictor.
>> >
>> > 2. Modify psychoacoustic to use prediction gain for bit allocation.
>> Right
>> > now ADPCM encoded block can get some extra bits.
>> >
>> > 3. Tuning the prediction gain threshold.
>> >
>> >
>> > Thank you.
>> > --
>> > Daniil Cherednik
>> >
>> > _______________________________________________
>> > ffmpeg-devel mailing list
>> > ffmpeg-devel at ffmpeg.org
>> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >
>> >
>> >+static int64_t calc_corr(const int32_t *x, int len, int j, int k)
>>
>> Add inline attrib? Seems appropriate here.
>>
>>
>> >+for (n = 0; n < len; n++) {
>> >+        s += MUL64(x[n-j], x[n-k]);
>> >+    }
>>
>> For loops with 1 line we leave the brackets out.
>>
>>
>> >+for (i = 0; i <= DCA_ADPCM_COEFFS; i++) {
>> >+        for (j = i; j <= DCA_ADPCM_COEFFS; j++) {
>> >+            corr[k++] = calc_corr(in+4, len, i, j);
>> >+        }
>> >+    }
>>
>> Same
>>
>>
>> >+    for (i = 0; i < len + DCA_ADPCM_COEFFS; i++) {
>> >+        max |= FFABS(in[i]);
>> >+    }
>>
>> Same
>>
>>
>> >for (ch = 0; ch < c->fullband_channels; ch++) {
>> >+        for (band = 0; band < 32; band++) {
>> >+            if (c->prediction_mode[ch][band] >= 0) {
>> >+                quantize_adpcm_subband(c, ch, band);
>> >+            }
>> >+        }
>> >+    }
>>
>> Same
>>
>>
>> >+    for (ch = 0; ch < c->fullband_channels; ch++) {
>> >+        for (band = 0; band < 32; band++) {
>> >+            if (c->prediction_mode[ch][band] == -1) {
>> >+                for (sample = 0; sample < SUBBAND_SAMPLES; sample++) {
>> >+                    c->quantized[ch][band][sample] =
>> quantize_value(c->subband[ch][band][sample], c->quant[ch][band]);
>> >+                }
>> >+            }
>> >+        }
>> >+    }
>>
>> Same, 4 whole whitespace lines added here.
>>
>>
>> >+    if (c->bitrate_index == 3) {
>> >+        step_size = ff_dca_lossless_quant[c->abits[ch][band]];
>> >+    } else {
>> >+        step_size = ff_dca_lossy_quant[c->abits[ch][band]];
>> >+    }
>>
>> Same
>>
>>
>> >for (;;) {
>>
>> while (1) {
>>
>> >+        if (i++ == last_pos)
>> >+            break;
>>
>> Better yet remove the infinite loop and just use a normal for () loop.
>>
>>
>> >+static inline void ff_dca_core_dequantize(int32_t *output, const int32_t
>> *input,
>> >+                              int32_t step_size, int32_t scale, int
>> residual, int len)
>>
>> Fix second line's alignment.
>>
>>
>> >+struct premultiplied_coeffs {
>> >+    int32_t aa[10];
>> >+};
>>
>> I think it would be simpler to just use int32_t premultiplied_coeffs[10]
>> instead of a struct.
>>
>>
>> Apart from these style issues patch looks fine. I'll be able to test it in
>> a day.
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>
>
>
>
> --
> Daniil Cherednik
>



-- 
Daniil Cherednik
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