avcodec: add ADPCM AGM decoder

1 files changed, 58 insertions, 0 deletions

diff --git a/libavcodec/adpcm.c b/libavcodec/adpcm.c
index aa9c7c5c4f..ede0130bf1 100644
--- a/libavcodec/adpcm.c
+++ b/libavcodec/adpcm.c
@@ -177,6 +177,50 @@ static av_cold int adpcm_decode_init(AVCodecContext * avctx)
     return 0;
 }
 
+static inline int16_t adpcm_agm_expand_nibble(ADPCMChannelStatus *c, int8_t nibble)
+{
+    int delta, pred, step, add;
+
+    pred = c->predictor;
+    delta = nibble & 7;
+    step = c->step;
+    add = (delta * 2 + 1) * step;
+    if (add < 0)
+        add = add + 7;
+
+    if ((nibble & 8) == 0)
+        pred = av_clip(pred + (add >> 3), -32767, 32767);
+    else
+        pred = av_clip(pred - (add >> 3), -32767, 32767);
+
+    switch (delta) {
+    case 7:
+        step *= 0x99;
+        break;
+    case 6:
+        c->step = av_clip(c->step * 2, 127, 24576);
+        c->predictor = pred;
+        return pred;
+    case 5:
+        step *= 0x66;
+        break;
+    case 4:
+        step *= 0x4d;
+        break;
+    default:
+        step *= 0x39;
+        break;
+    }
+
+    if (step < 0)
+        step += 0x3f;
+
+    c->step = step >> 6;
+    c->step = av_clip(c->step, 127, 24576);
+    c->predictor = pred;
+    return pred;
+}
+
 static inline int16_t adpcm_ima_expand_nibble(ADPCMChannelStatus *c, int8_t nibble, int shift)
 {
     int step_index;
@@ -549,6 +593,7 @@ static int get_nb_samples(AVCodecContext *avctx, GetByteContext *gb,
     header_size = 0;
     switch (avctx->codec->id) {
         case AV_CODEC_ID_ADPCM_4XM:
+        case AV_CODEC_ID_ADPCM_AGM:
         case AV_CODEC_ID_ADPCM_IMA_DAT4:
         case AV_CODEC_ID_ADPCM_IMA_ISS:     header_size = 4 * ch;      break;
         case AV_CODEC_ID_ADPCM_IMA_AMV:     header_size = 8;           break;
@@ -863,6 +908,18 @@ static int adpcm_decode_frame(AVCodecContext *avctx, void *data,
             }
         }
         break;
+    case AV_CODEC_ID_ADPCM_AGM:
+        for (i = 0; i < avctx->channels; i++)
+            c->status[i].predictor = sign_extend(bytestream2_get_le16u(&gb), 16);
+        for (i = 0; i < avctx->channels; i++)
+            c->status[i].step = sign_extend(bytestream2_get_le16u(&gb), 16);
+
+        for (n = 0; n < nb_samples >> (1 - st); n++) {
+            int v = bytestream2_get_byteu(&gb);
+            *samples++ = adpcm_agm_expand_nibble(&c->status[0], v & 0xF);
+            *samples++ = adpcm_agm_expand_nibble(&c->status[st], v >> 4 );
+        }
+        break;
     case AV_CODEC_ID_ADPCM_MS:
     {
         int block_predictor;
@@ -1729,6 +1786,7 @@ AVCodec ff_ ## name_ ## _decoder = {                        \
 /* Note: Do not forget to add new entries to the Makefile as well. */
 ADPCM_DECODER(AV_CODEC_ID_ADPCM_4XM,         sample_fmts_s16p, adpcm_4xm,         "ADPCM 4X Movie");
 ADPCM_DECODER(AV_CODEC_ID_ADPCM_AFC,         sample_fmts_s16p, adpcm_afc,         "ADPCM Nintendo Gamecube AFC");
+ADPCM_DECODER(AV_CODEC_ID_ADPCM_AGM,         sample_fmts_s16,  adpcm_agm,         "ADPCM AmuseGraphics Movie");
 ADPCM_DECODER(AV_CODEC_ID_ADPCM_AICA,        sample_fmts_s16p, adpcm_aica,        "ADPCM Yamaha AICA");
 ADPCM_DECODER(AV_CODEC_ID_ADPCM_CT,          sample_fmts_s16,  adpcm_ct,          "ADPCM Creative Technology");
 ADPCM_DECODER(AV_CODEC_ID_ADPCM_DTK,         sample_fmts_s16p, adpcm_dtk,         "ADPCM Nintendo Gamecube DTK");