8svx/iff: fix decoding of compressed stereo 8svx files.

Make the iff demuxer send the whole audio chunk to the decoder as a
single packet and move stereo interleaving from the iff demuxer to the
decoder.

Based on a patch by Stefano Sabatini.
git.videolan.org/ffmpeg.git
commit e280a4da

libavcodec/8svx.c

@@ -32,8 +32,14 @@
 
 /** decoder context */
 typedef struct EightSvxContext {
-    uint8_t fib_acc;
+    uint8_t fib_acc[2];
     const int8_t *table;
+
+    /* buffer used to store the whole first packet.
+       data is only sent as one large packet */
+    uint8_t *data[2];
+    int data_size;
+    int data_idx;
 } EightSvxContext;
 
 static const int8_t fibonacci[16]   = { -34, -21, -13,  -8, -5, -3, -2, -1,
@@ -41,6 +47,8 @@ static const int8_t fibonacci[16]   = { -34, -21, -13,  -8, -5, -3, -2, -1,
 static const int8_t exponential[16] = { -128, -64, -32, -16, -8, -4, -2, -1,
                                            0,   1,   2,   4,  8, 16, 32, 64 };
 
+#define MAX_FRAME_SIZE 32768
+
 /**
  * Delta decode the compressed values in src, and put the resulting
  * decoded samples in dst.
@@ -48,16 +56,18 @@ static const int8_t exponential[16] = { -128, -64, -32, -16, -8, -4, -2, -1,
  * @param[in,out] state starting value. it is saved for use in the next call.
  */
 static void delta_decode(uint8_t *dst, const uint8_t *src, int src_size,
-                         uint8_t *state, const int8_t *table)
+                         uint8_t *state, const int8_t *table, int channels)
 {
     uint8_t val = *state;
 
     while (src_size--) {
         uint8_t d = *src++;
         val = av_clip_uint8(val + table[d & 0xF]);
-        *dst++ = val;
+        *dst = val;
+        dst += channels;
         val = av_clip_uint8(val + table[d >> 4]);
-        *dst++ = val;
+        *dst = val;
+        dst += channels;
     }
 
     *state = val;
@@ -67,33 +77,69 @@ static void delta_decode(uint8_t *dst, const uint8_t *src, int src_size,
 static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
                                  AVPacket *avpkt)
 {
-    const uint8_t *buf = avpkt->data;
-    int buf_size = avpkt->size;
     EightSvxContext *esc = avctx->priv_data;
+    int buf_size;
     uint8_t *out_data = data;
-    int consumed = buf_size;
+    int out_data_size;
+
+    /* for the first packet, copy data to buffer */
+    if (avpkt->data) {
+        int chan_size = (avpkt->size / avctx->channels) - 2;
 
-    if(avctx->frame_number == 0) {
-        if (buf_size < 2) {
+        if (avpkt->size < 2) {
             av_log(avctx, AV_LOG_ERROR, "packet size is too small\n");
             return AVERROR(EINVAL);
         }
-        esc->fib_acc = (int8_t)buf[1] + 128;
-        buf_size -= 2;
-        buf += 2;
+        if (esc->data[0]) {
+            av_log(avctx, AV_LOG_ERROR, "unexpected data after first packet\n");
+            return AVERROR(EINVAL);
+        }
+
+        esc->fib_acc[0] = avpkt->data[1] + 128;
+        if (avctx->channels == 2)
+            esc->fib_acc[1] = avpkt->data[2+chan_size+1] + 128;
+
+        esc->data_idx  = 0;
+        esc->data_size = chan_size;
+        if (!(esc->data[0] = av_malloc(chan_size)))
+            return AVERROR(ENOMEM);
+        if (avctx->channels == 2) {
+            if (!(esc->data[1] = av_malloc(chan_size))) {
+                av_freep(&esc->data[0]);
+                return AVERROR(ENOMEM);
+            }
+        }
+        memcpy(esc->data[0], &avpkt->data[2], chan_size);
+        if (avctx->channels == 2)
+            memcpy(esc->data[1], &avpkt->data[2+chan_size+2], chan_size);
+    }
+    if (!esc->data[0]) {
+        av_log(avctx, AV_LOG_ERROR, "unexpected empty packet\n");
+        return AVERROR(EINVAL);
     }
 
-    if (*data_size < buf_size * 2) {
+    /* decode next piece of data from the buffer */
+    buf_size = FFMIN(MAX_FRAME_SIZE, esc->data_size - esc->data_idx);
+    if (buf_size <= 0) {
+        *data_size = 0;
+        return avpkt->size;
+    }
+    out_data_size = buf_size * 2 * avctx->channels;
+    if (*data_size < out_data_size) {
         av_log(avctx, AV_LOG_ERROR, "Provided buffer with size %d is too small.\n",
                *data_size);
         return AVERROR(EINVAL);
     }
+    delta_decode(out_data, &esc->data[0][esc->data_idx], buf_size,
+                 &esc->fib_acc[0], esc->table, avctx->channels);
+    if (avctx->channels == 2) {
+        delta_decode(&out_data[1], &esc->data[1][esc->data_idx], buf_size,
+                    &esc->fib_acc[1], esc->table, avctx->channels);
+    }
+    esc->data_idx += buf_size;
+    *data_size = out_data_size;
 
-    delta_decode(out_data, buf, buf_size, &esc->fib_acc, esc->table);
-
-    *data_size = buf_size * 2;
-
-    return consumed;
+    return avpkt->size;
 }
 
 /** initialize 8svx decoder */
@@ -101,6 +147,11 @@ static av_cold int eightsvx_decode_init(AVCodecContext *avctx)
 {
     EightSvxContext *esc = avctx->priv_data;
 
+    if (avctx->channels < 1 || avctx->channels > 2) {
+        av_log(avctx, AV_LOG_ERROR, "8SVX does not support more than 2 channels\n");
+        return AVERROR(EINVAL);
+    }
+
     switch(avctx->codec->id) {
         case CODEC_ID_8SVX_FIB:
           esc->table = fibonacci;
@@ -115,13 +166,25 @@ static av_cold int eightsvx_decode_init(AVCodecContext *avctx)
     return 0;
 }
 
+static av_cold int eightsvx_decode_close(AVCodecContext *avctx)
+{
+    EightSvxContext *esc = avctx->priv_data;
+
+    av_freep(&esc->data[0]);
+    av_freep(&esc->data[1]);
+
+    return 0;
+}
+
 AVCodec ff_eightsvx_fib_decoder = {
   .name           = "8svx_fib",
   .type           = AVMEDIA_TYPE_AUDIO,
   .id             = CODEC_ID_8SVX_FIB,
   .priv_data_size = sizeof (EightSvxContext),
   .init           = eightsvx_decode_init,
+  .close          = eightsvx_decode_close,
   .decode         = eightsvx_decode_frame,
+  .capabilities   = CODEC_CAP_DELAY,
   .long_name      = NULL_IF_CONFIG_SMALL("8SVX fibonacci"),
 };
 
@@ -131,6 +194,8 @@ AVCodec ff_eightsvx_exp_decoder = {
   .id             = CODEC_ID_8SVX_EXP,
   .priv_data_size = sizeof (EightSvxContext),
   .init           = eightsvx_decode_init,
+  .close          = eightsvx_decode_close,
   .decode         = eightsvx_decode_frame,
+  .capabilities   = CODEC_CAP_DELAY,
   .long_name      = NULL_IF_CONFIG_SMALL("8SVX exponential"),
 };

libavformat/iff.c

@@ -59,8 +59,6 @@
 #define RIGHT   4
 #define STEREO  6
 
-#define PACKET_SIZE 1024
-
 typedef enum {
     COMP_NONE,
     COMP_FIB,
@@ -76,22 +74,9 @@ typedef struct {
     uint64_t  body_pos;
     uint32_t  body_size;
     uint32_t  sent_bytes;
-    uint32_t  audio_frame_count;
 } IffDemuxContext;
 
 
-static void interleave_stereo(const uint8_t *src, uint8_t *dest, int size)
-{
-    uint8_t *end = dest + size;
-    size = size>>1;
-
-    while(dest < end) {
-        *dest++ = *src;
-        *dest++ = *(src+size);
-        src++;
-    }
-}
-
 /* Metadata string read */
 static int get_metadata(AVFormatContext *s,
                         const char *const tag,
@@ -278,40 +263,20 @@ static int iff_read_packet(AVFormatContext *s,
 {
     IffDemuxContext *iff = s->priv_data;
     AVIOContext *pb = s->pb;
-    AVStream *st = s->streams[0];
     int ret;
 
     if(iff->sent_bytes >= iff->body_size)
-        return AVERROR(EIO);
-
-    if(st->codec->channels == 2) {
-        uint8_t sample_buffer[PACKET_SIZE];
+        return AVERROR_EOF;
 
-        ret = avio_read(pb, sample_buffer, PACKET_SIZE);
-        if(av_new_packet(pkt, PACKET_SIZE) < 0) {
-            av_log(s, AV_LOG_ERROR, "cannot allocate packet\n");
-            return AVERROR(ENOMEM);
-        }
-        interleave_stereo(sample_buffer, pkt->data, PACKET_SIZE);
-    } else if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
     ret = av_get_packet(pb, pkt, iff->body_size);
-    } else {
-        ret = av_get_packet(pb, pkt, PACKET_SIZE);
-    }
+    if (ret < 0)
+        return ret;
 
     if(iff->sent_bytes == 0)
         pkt->flags |= AV_PKT_FLAG_KEY;
-
-    if(st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
-        iff->sent_bytes += PACKET_SIZE;
-    } else {
     iff->sent_bytes = iff->body_size;
-    }
+
     pkt->stream_index = 0;
-    if(st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
-        pkt->pts = iff->audio_frame_count;
-        iff->audio_frame_count += ret / st->codec->channels;
-    }
     return ret;
 }