[FFmpeg-cvslog] vmdaudio: fix decoding of 16-bit audio format.
Justin Ruggles
git at videolan.org
Mon Sep 26 00:01:19 CEST 2011
ffmpeg | branch: master | Justin Ruggles <justin.ruggles at gmail.com> | Sun Sep 11 20:17:54 2011 -0400| [4568c2bf975e51d843bf1ff6ac06060a8a6291b3] | committer: Justin Ruggles
vmdaudio: fix decoding of 16-bit audio format.
The initial sample of each block is raw 16-bit PCM, not DPCM.
Fixes decoding of all samples in:
http://streams.videolan.org/samples/game-formats/sierra-vmd/Lighthouse/
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4568c2bf975e51d843bf1ff6ac06060a8a6291b3
---
libavcodec/vmdav.c | 120 ++++++++++++++++++++++++++++++++++-----------------
1 files changed, 80 insertions(+), 40 deletions(-)
diff --git a/libavcodec/vmdav.c b/libavcodec/vmdav.c
index 110d19c..4528996 100644
--- a/libavcodec/vmdav.c
+++ b/libavcodec/vmdav.c
@@ -417,9 +417,8 @@ static av_cold int vmdvideo_decode_end(AVCodecContext *avctx)
#define BLOCK_TYPE_SILENCE 3
typedef struct VmdAudioContext {
- AVCodecContext *avctx;
int out_bps;
- int predictors[2];
+ int chunk_size;
} VmdAudioContext;
static const uint16_t vmdaudio_table[128] = {
@@ -442,13 +441,23 @@ static av_cold int vmdaudio_decode_init(AVCodecContext *avctx)
{
VmdAudioContext *s = avctx->priv_data;
- s->avctx = avctx;
+ if (avctx->channels < 1 || avctx->channels > 2) {
+ av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
+ return AVERROR(EINVAL);
+ }
+ if (avctx->block_align < 1) {
+ av_log(avctx, AV_LOG_ERROR, "invalid block align\n");
+ return AVERROR(EINVAL);
+ }
+
if (avctx->bits_per_coded_sample == 16)
avctx->sample_fmt = AV_SAMPLE_FMT_S16;
else
avctx->sample_fmt = AV_SAMPLE_FMT_U8;
s->out_bps = av_get_bytes_per_sample(avctx->sample_fmt);
+ s->chunk_size = avctx->block_align + avctx->channels * (s->out_bps == 2);
+
av_log(avctx, AV_LOG_DEBUG, "%d channels, %d bits/sample, "
"block align = %d, sample rate = %d\n",
avctx->channels, avctx->bits_per_coded_sample, avctx->block_align,
@@ -457,41 +466,33 @@ static av_cold int vmdaudio_decode_init(AVCodecContext *avctx)
return 0;
}
-static void vmdaudio_decode_audio(VmdAudioContext *s, unsigned char *data,
- const uint8_t *buf, int buf_size, int stereo)
+static void decode_audio_s16(int16_t *out, const uint8_t *buf, int buf_size,
+ int channels)
{
- int i;
- int chan = 0;
- int16_t *out = (int16_t*)data;
-
- for(i = 0; i < buf_size; i++) {
- if(buf[i] & 0x80)
- s->predictors[chan] -= vmdaudio_table[buf[i] & 0x7F];
- else
- s->predictors[chan] += vmdaudio_table[buf[i]];
- s->predictors[chan] = av_clip_int16(s->predictors[chan]);
- out[i] = s->predictors[chan];
- chan ^= stereo;
+ int ch;
+ const uint8_t *buf_end = buf + buf_size;
+ int predictor[2];
+ int st = channels - 1;
+
+ /* decode initial raw sample */
+ for (ch = 0; ch < channels; ch++) {
+ predictor[ch] = (int16_t)AV_RL16(buf);
+ buf += 2;
+ *out++ = predictor[ch];
}
-}
-static int vmdaudio_loadsound(VmdAudioContext *s, unsigned char *data,
- const uint8_t *buf, int silent_chunks, int data_size)
-{
- int silent_size = s->avctx->block_align * silent_chunks * s->out_bps;
-
- if (silent_chunks) {
- memset(data, s->out_bps == 2 ? 0x00 : 0x80, silent_size);
- data += silent_size;
- }
- if (s->avctx->bits_per_coded_sample == 16)
- vmdaudio_decode_audio(s, data, buf, data_size, s->avctx->channels == 2);
- else {
- /* just copy the data */
- memcpy(data, buf, data_size);
+ /* decode DPCM samples */
+ ch = 0;
+ while (buf < buf_end) {
+ uint8_t b = *buf++;
+ if (b & 0x80)
+ predictor[ch] -= vmdaudio_table[b & 0x7F];
+ else
+ predictor[ch] += vmdaudio_table[b];
+ predictor[ch] = av_clip_int16(predictor[ch]);
+ *out++ = predictor[ch];
+ ch ^= st;
}
-
- return silent_size + data_size * s->out_bps;
}
static int vmdaudio_decode_frame(AVCodecContext *avctx,
@@ -499,10 +500,13 @@ static int vmdaudio_decode_frame(AVCodecContext *avctx,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
+ const uint8_t *buf_end;
int buf_size = avpkt->size;
VmdAudioContext *s = avctx->priv_data;
- int block_type, silent_chunks;
- unsigned char *output_samples = (unsigned char *)data;
+ int block_type, silent_chunks, audio_chunks;
+ int nb_samples, out_size;
+ uint8_t *output_samples_u8 = data;
+ int16_t *output_samples_s16 = data;
if (buf_size < 16) {
av_log(avctx, AV_LOG_WARNING, "skipping small junk packet\n");
@@ -518,10 +522,16 @@ static int vmdaudio_decode_frame(AVCodecContext *avctx,
buf += 16;
buf_size -= 16;
+ /* get number of silent chunks */
silent_chunks = 0;
if (block_type == BLOCK_TYPE_INITIAL) {
- uint32_t flags = AV_RB32(buf);
- silent_chunks = av_popcount(flags);
+ uint32_t flags;
+ if (buf_size < 4) {
+ av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
+ return AVERROR(EINVAL);
+ }
+ flags = AV_RB32(buf);
+ silent_chunks = av_popcount(flags);
buf += 4;
buf_size -= 4;
} else if (block_type == BLOCK_TYPE_SILENCE) {
@@ -530,11 +540,41 @@ static int vmdaudio_decode_frame(AVCodecContext *avctx,
}
/* ensure output buffer is large enough */
- if (*data_size < (avctx->block_align*silent_chunks + buf_size) * s->out_bps)
+ audio_chunks = buf_size / s->chunk_size;
+ nb_samples = ((silent_chunks + audio_chunks) * avctx->block_align) / avctx->channels;
+ out_size = nb_samples * avctx->channels * s->out_bps;
+ if (*data_size < out_size)
return -1;
- *data_size = vmdaudio_loadsound(s, output_samples, buf, silent_chunks, buf_size);
+ /* decode silent chunks */
+ if (silent_chunks > 0) {
+ int silent_size = avctx->block_align * silent_chunks;
+ if (s->out_bps == 2) {
+ memset(output_samples_s16, 0x00, silent_size * 2);
+ output_samples_s16 += silent_size;
+ } else {
+ memset(output_samples_u8, 0x80, silent_size);
+ output_samples_u8 += silent_size;
+ }
+ }
+
+ /* decode audio chunks */
+ if (audio_chunks > 0) {
+ buf_end = buf + buf_size;
+ while (buf < buf_end) {
+ if (s->out_bps == 2) {
+ decode_audio_s16(output_samples_s16, buf, s->chunk_size,
+ avctx->channels);
+ output_samples_s16 += avctx->block_align;
+ } else {
+ memcpy(output_samples_u8, buf, s->chunk_size);
+ output_samples_u8 += avctx->block_align;
+ }
+ buf += s->chunk_size;
+ }
+ }
+ *data_size = out_size;
return avpkt->size;
}
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