avcodec: add SDX2 DPCM decoder

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 28 insertions, 4 deletions

diff --git a/libavcodec/dpcm.c b/libavcodec/dpcm.c
index c13945edb6..52a2c616db 100644
--- a/libavcodec/dpcm.c
+++ b/libavcodec/dpcm.c
@@ -44,7 +44,7 @@
 #include "mathops.h"
 
 typedef struct DPCMContext {
-    int16_t roq_square_array[256];
+    int16_t square_array[256];
     int sample[2];                  ///< previous sample (for SOL_DPCM)
     const int8_t *sol_table;        ///< delta table for SOL_DPCM
 } DPCMContext;
@@ -130,8 +130,8 @@ static av_cold int dpcm_decode_init(AVCodecContext *avctx)
         /* initialize square table */
         for (i = 0; i < 128; i++) {
             int16_t square = i * i;
-            s->roq_square_array[i      ] =  square;
-            s->roq_square_array[i + 128] = -square;
+            s->square_array[i      ] =  square;
+            s->square_array[i + 128] = -square;
         }
         break;
 
@@ -153,6 +153,13 @@ static av_cold int dpcm_decode_init(AVCodecContext *avctx)
         }
         break;
 
+    case AV_CODEC_ID_SDX2_DPCM:
+        for (i = -128; i < 128; i++) {
+            int16_t square = i * i * 2;
+            s->square_array[i+128] = i < 0 ? -square: square;
+        }
+        break;
+
     default:
         break;
     }
@@ -200,6 +207,9 @@ static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
         else
             out = buf_size;
         break;
+    case AV_CODEC_ID_SDX2_DPCM:
+        out = buf_size;
+        break;
     }
     if (out <= 0) {
         av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
@@ -230,7 +240,7 @@ static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
 
         /* decode the samples */
         while (output_samples < samples_end) {
-            predictor[ch] += s->roq_square_array[bytestream2_get_byteu(&gb)];
+            predictor[ch] += s->square_array[bytestream2_get_byteu(&gb)];
             predictor[ch]  = av_clip_int16(predictor[ch]);
             *output_samples++ = predictor[ch];
 
@@ -318,6 +328,19 @@ static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
             }
         }
         break;
+
+    case AV_CODEC_ID_SDX2_DPCM:
+        while (output_samples < samples_end) {
+            int8_t n = bytestream2_get_byteu(&gb);
+
+            if (!(n & 1))
+                s->sample[ch] = 0;
+            s->sample[ch] += s->square_array[n + 128];
+            s->sample[ch]  = av_clip_int16(s->sample[ch]);
+            *output_samples++ = s->sample[ch];
+            ch ^= stereo;
+        }
+        break;
     }
 
     *got_frame_ptr = 1;
@@ -339,5 +362,6 @@ AVCodec ff_ ## name_ ## _decoder = {                        \
 
 DPCM_DECODER(AV_CODEC_ID_INTERPLAY_DPCM, interplay_dpcm, "DPCM Interplay");
 DPCM_DECODER(AV_CODEC_ID_ROQ_DPCM,       roq_dpcm,       "DPCM id RoQ");
+DPCM_DECODER(AV_CODEC_ID_SDX2_DPCM,      sdx2_dpcm,      "DPCM Squareroot-Delta-Exact");
 DPCM_DECODER(AV_CODEC_ID_SOL_DPCM,       sol_dpcm,       "DPCM Sol");
 DPCM_DECODER(AV_CODEC_ID_XAN_DPCM,       xan_dpcm,       "DPCM Xan");