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avcodec/wavarc: fix bugs in arithmetic coding mode

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This commit is contained in:
Paul B Mahol
2023-09-02 15:46:24 +02:00
parent fb06a44360
commit 9c2206a13b
1 changed files with 48 additions and 26 deletions
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74
libavcodec/wavarc.c
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@@ -412,13 +412,13 @@ static int ac_init(AVCodecContext *avctx,
return 0;
}
static unsigned ac_get_prob(WavArcContext *s)
static uint16_t ac_get_prob(WavArcContext *s)
{
return ((s->freq_range - 1) + ((unsigned)s->ac_value - (unsigned)s->ac_low) *
(unsigned)s->freq_range) / (((unsigned)s->ac_high - (unsigned)s->ac_low) + 1) & 0xffffu;
return ((s->freq_range - 1) + (s->ac_value - s->ac_low) * s->freq_range) /
((s->ac_high - s->ac_low) + 1U);
}
static unsigned ac_map_symbol(WavArcContext *s, unsigned prob)
static uint8_t ac_map_symbol(WavArcContext *s, uint16_t prob)
{
int idx = 255;
@@ -435,33 +435,43 @@ static int ac_normalize(AVCodecContext *avctx, WavArcContext *s, GetBitContext *
{
int range;
range = (unsigned)s->ac_high - (unsigned)s->ac_low + 1;
s->ac_high = (int16_t)((range * (unsigned)s->range_high) / (unsigned)s->freq_range) + -1 + s->ac_low;
s->ac_low += (int16_t)((range * (unsigned)s->range_low) / (unsigned)s->freq_range);
if (s->ac_high < s->ac_low)
goto fail;
range = (s->ac_high - s->ac_low) + 1;
s->ac_high = (range * s->range_high) / s->freq_range + s->ac_low - 1;
s->ac_low += (range * s->range_low) / s->freq_range;
if (s->ac_high < s->ac_low)
goto fail;
for (;;) {
if ((s->ac_high & 0x8000) != (s->ac_low & 0x8000)) {
if ((s->ac_low & 0x4000) == 0 || (s->ac_high & 0x4000) != 0)
if (((s->ac_low & 0x4000) == 0) || ((s->ac_high & 0x4000) != 0))
return 0;
s->ac_value ^= 0x4000;
s->ac_low &= 0x3fff;
s->ac_high |= 0x4000;
}
s->ac_low = s->ac_low << 1;
s->ac_high = s->ac_high * 2 + 1;
if (s->ac_high < s->ac_low) {
av_log(avctx, AV_LOG_ERROR, "invalid state\n");
return AVERROR_INVALIDDATA;
}
s->ac_low = s->ac_low * 2;
s->ac_high = s->ac_high * 2 | 1;
if (s->ac_high < s->ac_low)
goto fail;
if (get_bits_left(gb) <= 0) {
av_log(avctx, AV_LOG_ERROR, "overread in arithmetic coder\n");
return AVERROR_INVALIDDATA;
goto fail;
}
s->ac_value = s->ac_value * 2 + get_bits1(gb);
if (s->ac_low > s->ac_value || s->ac_high < s->ac_value)
goto fail;
}
fail:
av_log(avctx, AV_LOG_ERROR, "invalid state\n");
return AVERROR_INVALIDDATA;
}
static void ac_init_model(WavArcContext *s)
@@ -484,11 +494,11 @@ static int ac_read_model(AVCodecContext *avctx,
end = get_bits(gb, 8);
for (;;) {
while (start <= end)
while (start <= end) {
if (get_bits_left(gb) < 8)
return AVERROR_INVALIDDATA;
s->model[start++] = get_bits(gb, 8);
if (get_bits_left(gb) < 8)
return AVERROR_INVALIDDATA;
}
if (get_bits_left(gb) < 8)
return AVERROR_INVALIDDATA;
@@ -568,9 +578,9 @@ static int decode_5elp(AVCodecContext *avctx,
}
for (int n = 0; n < s->nb_samples; n++) {
unsigned prob = ac_get_prob(s);
prob = ac_map_symbol(s, prob);
ac_out[n] = prob - 0x80;
uint16_t prob = ac_get_prob(s);
int ac = ac_map_symbol(s, prob);
ac_out[n] = ac - 0x80;
if ((ret = ac_normalize(avctx, s, &ac_gb)) < 0)
return ret;
}
@@ -620,11 +630,16 @@ static int decode_5elp(AVCodecContext *avctx,
case 20:
case 7:
for (int n = 0; n < s->nb_samples; n++)
samples[n + 70] = ac_out[n] + samples[n + 69] * 3 - samples[n + 68] * 3 + samples[n + 67];
samples[n + 70] += ac_out[n] + samples[n + 69] * 3 - samples[n + 68] * 3 + samples[n + 67];
finished = 1;
break;
case 19:
case 6:
for (int n = 0; n < 70; n++) {
ac_pred[n] = samples[n];
samples[n] = 0;
}
for (int n = 0; n < s->nb_samples; n++) {
int sum = 15;
@@ -633,24 +648,31 @@ static int decode_5elp(AVCodecContext *avctx,
samples[n + 70] += ac_out[n] + (sum >> 4);
}
for (int n = 0; n < 70; n++)
samples[n] = ac_pred[n];
for (int n = 0; n < s->nb_samples; n++)
samples[n + 70] += ac_out[n] + samples[n + 69] * 3 - samples[n + 68] * 3 + samples[n + 67];
finished = 1;
break;
case 18:
case 5:
for (int n = 0; n < s->nb_samples; n++)
samples[n + 70] = ac_out[n] + samples[n + 69] * 2 - samples[n + 68];
samples[n + 70] += ac_out[n] + samples[n + 69] * 2 - samples[n + 68];
finished = 1;
break;
case 17:
case 4:
for (int n = 0; n < s->nb_samples; n++)
samples[n + 70] = ac_out[n];
samples[n + 70] += ac_out[n];
finished = 1;
break;
case 16:
case 3:
for (int n = 0; n < s->nb_samples; n++)
samples[n + 70] = ac_out[n] + samples[n + 69];
samples[n + 70] += ac_out[n] + samples[n + 69];
finished = 1;
break;
case 15: