[FFmpeg-devel] [PATCH 2/2] avcodec/apedec: Implement interim mode detection
Michael Niedermayer
michael at niedermayer.cc
Sat Aug 26 19:53:50 EEST 2023
Fixes: NoLegacy.ape
Found-by: Matt Ashland <mail at monkeysaudio.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
libavcodec/apedec.c | 106 +++++++++++++++++++++++++++++++++++---------
1 file changed, 84 insertions(+), 22 deletions(-)
diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
index 8bd625ca05..249fc22e24 100644
--- a/libavcodec/apedec.c
+++ b/libavcodec/apedec.c
@@ -171,6 +171,9 @@ typedef struct APEContext {
int32_t *decoded_buffer;
int decoded_size;
int32_t *decoded[MAX_CHANNELS]; ///< decoded data for each channel
+ int32_t *interim_buffer;
+ int interim_size;
+ int32_t *interim[MAX_CHANNELS]; ///< decoded data for each channel
int blocks_per_loop; ///< maximum number of samples to decode for each call
int16_t* filterbuf[APE_FILTER_LEVELS]; ///< filter memory
@@ -187,6 +190,7 @@ typedef struct APEContext {
const uint8_t *ptr; ///< current position in frame data
int error;
+ int interim_mode;
void (*entropy_decode_mono)(struct APEContext *ctx, int blockstodecode);
void (*entropy_decode_stereo)(struct APEContext *ctx, int blockstodecode);
@@ -223,6 +227,7 @@ static av_cold int ape_decode_close(AVCodecContext *avctx)
av_freep(&s->filterbuf[i]);
av_freep(&s->decoded_buffer);
+ av_freep(&s->interim_buffer);
av_freep(&s->data);
s->decoded_size = s->data_size = 0;
@@ -248,12 +253,15 @@ static av_cold int ape_decode_init(AVCodecContext *avctx)
switch (s->bps) {
case 8:
avctx->sample_fmt = AV_SAMPLE_FMT_U8P;
+ s->interim_mode = 0;
break;
case 16:
avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
+ s->interim_mode = 0;
break;
case 24:
avctx->sample_fmt = AV_SAMPLE_FMT_S32P;
+ s->interim_mode = -1;
break;
default:
avpriv_request_sample(avctx,
@@ -1181,7 +1189,7 @@ static av_always_inline int predictor_update_filter(APEPredictor64 *p,
const int decoded, const int filter,
const int delayA, const int delayB,
const int adaptA, const int adaptB,
- int compression_level)
+ int interim_mode)
{
int64_t predictionA, predictionB;
int32_t sign;
@@ -1209,7 +1217,7 @@ static av_always_inline int predictor_update_filter(APEPredictor64 *p,
p->buf[delayB - 3] * p->coeffsB[filter][3] +
p->buf[delayB - 4] * p->coeffsB[filter][4];
- if (compression_level < COMPRESSION_LEVEL_INSANE) {
+ if (interim_mode < 1) {
predictionA = (int32_t)predictionA;
predictionB = (int32_t)predictionB;
p->lastA[filter] = decoded + ((int32_t)(predictionA + (predictionB >> 1)) >> 10);
@@ -1234,33 +1242,74 @@ static av_always_inline int predictor_update_filter(APEPredictor64 *p,
static void predictor_decode_stereo_3950(APEContext *ctx, int count)
{
- APEPredictor64 *p = &ctx->predictor64;
- int32_t *decoded0 = ctx->decoded[0];
- int32_t *decoded1 = ctx->decoded[1];
+ APEPredictor64 *p_default = &ctx->predictor64;
+ APEPredictor64 p_interim;
+ int lcount = count;
+ int num_passes = 1;
ape_apply_filters(ctx, ctx->decoded[0], ctx->decoded[1], count);
+ if (ctx->interim_mode == -1) {
+ p_interim = *p_default;
+ num_passes ++;
+ memcpy(ctx->interim[0], ctx->decoded[0], sizeof(*ctx->interim[0])*count);
+ memcpy(ctx->interim[1], ctx->decoded[1], sizeof(*ctx->interim[1])*count);
+ }
- while (count--) {
- /* Predictor Y */
- *decoded0 = predictor_update_filter(p, *decoded0, 0, YDELAYA, YDELAYB,
- YADAPTCOEFFSA, YADAPTCOEFFSB,
- ctx->compression_level);
- decoded0++;
- *decoded1 = predictor_update_filter(p, *decoded1, 1, XDELAYA, XDELAYB,
- XADAPTCOEFFSA, XADAPTCOEFFSB,
- ctx->compression_level);
- decoded1++;
+ for(int pass = 0; pass < num_passes; pass++) {
+ int32_t *decoded0, *decoded1;
+ int interim_mode = ctx->interim_mode > 0 || pass;
+ APEPredictor64 *p;
- /* Combined */
- p->buf++;
+ if (pass) {
+ p = &p_interim;
+ decoded0 = ctx->interim[0];
+ decoded1 = ctx->interim[1];
+ } else {
+ p = p_default;
+ decoded0 = ctx->decoded[0];
+ decoded1 = ctx->decoded[1];
+ }
+ p->buf = p->historybuffer;
+
+ count = lcount;
+ while (count--) {
+ /* Predictor Y */
+ int32_t a0 = predictor_update_filter(p, *decoded0, 0, YDELAYA, YDELAYB,
+ YADAPTCOEFFSA, YADAPTCOEFFSB,
+ interim_mode);
+ int32_t a1 = predictor_update_filter(p, *decoded1, 1, XDELAYA, XDELAYB,
+ XADAPTCOEFFSA, XADAPTCOEFFSB,
+ interim_mode);
+ *decoded0++ = a0;
+ *decoded1++ = a1;
+ if (num_passes > 1) {
+ int32_t left = a1 - (unsigned)(a0 / 2);
+ int32_t right = left + a0;
+
+ if (FFMAX(FFABS(left), FFABS(right)) > (1<<23)) {
+ ctx->interim_mode = !interim_mode;
+ av_log(ctx->avctx, AV_LOG_VERBOSE, "Interim mode: %d\n", ctx->interim_mode);
+ break;
+ }
+ }
- /* Have we filled the history buffer? */
- if (p->buf == p->historybuffer + HISTORY_SIZE) {
- memmove(p->historybuffer, p->buf,
- PREDICTOR_SIZE * sizeof(*p->historybuffer));
- p->buf = p->historybuffer;
+ /* Combined */
+ p->buf++;
+
+ /* Have we filled the history buffer? */
+ if (p->buf == p->historybuffer + HISTORY_SIZE) {
+ memmove(p->historybuffer, p->buf,
+ PREDICTOR_SIZE * sizeof(*p->historybuffer));
+ p->buf = p->historybuffer;
+ }
}
}
+ if (num_passes > 1 && ctx->interim_mode > 0) {
+ memcpy(ctx->decoded[0], ctx->interim[0], sizeof(*ctx->interim[0])*lcount);
+ memcpy(ctx->decoded[1], ctx->interim[1], sizeof(*ctx->interim[1])*lcount);
+ *p_default = p_interim;
+ p_default->buf = p_default->historybuffer;
+ }
}
static void predictor_decode_mono_3950(APEContext *ctx, int count)
@@ -1590,6 +1639,19 @@ static int ape_decode_frame(AVCodecContext *avctx, AVFrame *frame,
s->decoded[0] = s->decoded_buffer;
s->decoded[1] = s->decoded_buffer + FFALIGN(blockstodecode, 8);
+ if (s->interim_mode < 0) {
+ av_fast_malloc(&s->interim_buffer, &s->interim_size, decoded_buffer_size);
+ if (!s->interim_buffer)
+ return AVERROR(ENOMEM);
+ memset(s->interim_buffer, 0, decoded_buffer_size);
+ s->interim[0] = s->interim_buffer;
+ s->interim[1] = s->interim_buffer + FFALIGN(blockstodecode, 8);
+ } else {
+ av_freep(&s->interim_buffer);
+ s->interim_size = 0;
+ memset(s->interim, 0, sizeof(s->interim));
+ }
+
s->error=0;
if ((s->channels == 1) || (s->frameflags & APE_FRAMECODE_PSEUDO_STEREO))
--
2.17.1
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