lavf/utils: Add ff_get_packet_palette()

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/internal.h

@@ -573,4 +573,16 @@ int ff_parse_creation_time_metadata(AVFormatContext *s, int64_t *timestamp, int
  */
 int ff_reshuffle_raw_rgb(AVFormatContext *s, AVPacket **ppkt, AVCodecContext *enc, int expected_stride);
 
+/**
+ * Retrieves the palette from a packet, either from side data, or
+ * appended to the video data in the packet itself (raw video only).
+ * It is commonly used after a call to ff_reshuffle_raw_rgb().
+ *
+ * Use 0 for the ret parameter to check for side data only.
+ *
+ * @param pkt pointer to the packet before calling ff_reshuffle_raw_rgb()
+ * @param ret return value from ff_reshuffle_raw_rgb(), or 0
+ */
+int ff_get_packet_palette(AVFormatContext *s, AVPacket *pkt, int ret, const uint8_t **palette);
+
 #endif /* AVFORMAT_INTERNAL_H */

libavformat/utils.c

@@ -4759,3 +4759,19 @@ int ff_parse_creation_time_metadata(AVFormatContext *s, int64_t *timestamp, int
     }
     return 0;
 }
+
+int ff_get_packet_palette(AVFormatContext *s, AVPacket *pkt, int ret, const uint8_t **palette)
+{
+    int size;
+
+    *palette = av_packet_get_side_data(pkt, AV_PKT_DATA_PALETTE, &size);
+    if (*palette && size != AVPALETTE_SIZE) {
+        av_log(s, AV_LOG_ERROR, "Invalid palette side data\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (!*palette && ret == CONTAINS_PAL)
+        *palette = pkt->data + pkt->size - AVPALETTE_SIZE;
+
+    return 0;
+}