avcodec/codec_internal: Constify AVPacket in decode_sub cb

No subtitle decoder ever modifies the AVPacket given to it.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/assdec.c

@@ -41,7 +41,7 @@ static av_cold int ass_decode_init(AVCodecContext *avctx)
 }
 
 static int ass_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                            int *got_sub_ptr, AVPacket *avpkt)
+                            int *got_sub_ptr, const AVPacket *avpkt)
 {
     if (avpkt->size <= 0)
         return avpkt->size;

libavcodec/ccaption_dec.c

@@ -839,7 +839,7 @@ static int process_cc608(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
 }
 
 static int decode(AVCodecContext *avctx, AVSubtitle *sub,
-                  int *got_sub, AVPacket *avpkt)
+                  int *got_sub, const AVPacket *avpkt)
 {
     CCaptionSubContext *ctx = avctx->priv_data;
     int64_t in_time = sub->pts;

libavcodec/codec_internal.h

@@ -184,7 +184,7 @@ typedef struct FFCodec {
          * Apart from that this is like the decode callback.
          */
         int (*decode_sub)(struct AVCodecContext *avctx, struct AVSubtitle *sub,
-                          int *got_frame_ptr, struct AVPacket *avpkt);
+                          int *got_frame_ptr, const struct AVPacket *avpkt);
         /**
          * Decode API with decoupled packet/frame dataflow.
          * cb is in this state if cb_type is FF_CODEC_CB_TYPE_RECEIVE_FRAME.

libavcodec/dvbsubdec.c

@@ -1608,7 +1608,7 @@ static int dvbsub_display_end_segment(AVCodecContext *avctx, const uint8_t *buf,
 }
 
 static int dvbsub_decode(AVCodecContext *avctx, AVSubtitle *sub,
-                         int *got_sub_ptr, AVPacket *avpkt)
+                         int *got_sub_ptr, const AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;

libavcodec/dvdsubdec.c

@@ -549,7 +549,7 @@ static int append_to_cached_buf(AVCodecContext *avctx,
 }
 
 static int dvdsub_decode(AVCodecContext *avctx, AVSubtitle *sub,
-                         int *data_size, AVPacket *avpkt)
+                         int *data_size, const AVPacket *avpkt)
 {
     DVDSubContext *ctx = avctx->priv_data;
     const uint8_t *buf = avpkt->data;

libavcodec/jacosubdec.c

@@ -163,7 +163,7 @@ static void jacosub_to_ass(AVCodecContext *avctx, AVBPrint *dst, const char *src
 }
 
 static int jacosub_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                                int *got_sub_ptr, AVPacket *avpkt)
+                                int *got_sub_ptr, const AVPacket *avpkt)
 {
     int ret;
     const char *ptr = avpkt->data;

libavcodec/libaribb24.c

@@ -284,7 +284,7 @@ next_region:
 }
 
 static int libaribb24_decode(AVCodecContext *avctx, AVSubtitle *sub,
-                             int *got_sub_ptr, AVPacket *pkt)
+                             int *got_sub_ptr, const AVPacket *pkt)
 {
     Libaribb24Context *b24 = avctx->priv_data;
     size_t parsed_data_size = 0;

libavcodec/libzvbi-teletextdec.c

@@ -638,7 +638,7 @@ static int slice_to_vbi_lines(TeletextContext *ctx, uint8_t* buf, int size)
 }
 
 static int teletext_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                                 int *got_sub_ptr, AVPacket *pkt)
+                                 int *got_sub_ptr, const AVPacket *pkt)
 {
     TeletextContext *ctx = avctx->priv_data;
     int             ret = 0;

libavcodec/microdvddec.c

@@ -275,7 +275,7 @@ static void microdvd_close_no_persistent_tags(AVBPrint *new_line,
 }
 
 static int microdvd_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                                 int *got_sub_ptr, AVPacket *avpkt)
+                                 int *got_sub_ptr, const AVPacket *avpkt)
 {
     AVBPrint new_line;
     char *line = avpkt->data;

libavcodec/movtextdec.c

@@ -473,7 +473,7 @@ static int mov_text_init(AVCodecContext *avctx) {
 }
 
 static int mov_text_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                                 int *got_sub_ptr, AVPacket *avpkt)
+                                 int *got_sub_ptr, const AVPacket *avpkt)
 {
     MovTextContext *m = avctx->priv_data;
     int ret;

libavcodec/mpl2dec.c

@@ -64,7 +64,7 @@ static int mpl2_event_to_ass(AVBPrint *buf, const char *p)
 }
 
 static int mpl2_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                             int *got_sub_ptr, AVPacket *avpkt)
+                             int *got_sub_ptr, const AVPacket *avpkt)
 {
     int ret = 0;
     AVBPrint buf;

libavcodec/pgssubdec.c

@@ -590,7 +590,7 @@ static int display_end_segment(AVCodecContext *avctx, AVSubtitle *sub,
 }
 
 static int decode(AVCodecContext *avctx, AVSubtitle *sub,
-                  int *got_sub_ptr, AVPacket *avpkt)
+                  int *got_sub_ptr, const AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;

libavcodec/realtextdec.c

@@ -57,7 +57,7 @@ static int rt_event_to_ass(AVBPrint *buf, const char *p)
 }
 
 static int realtext_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                                 int *got_sub_ptr, AVPacket *avpkt)
+                                 int *got_sub_ptr, const AVPacket *avpkt)
 {
     int ret = 0;
     const char *ptr = avpkt->data;

libavcodec/samidec.c

@@ -133,7 +133,7 @@ end:
 }
 
 static int sami_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                             int *got_sub_ptr, AVPacket *avpkt)
+                             int *got_sub_ptr, const AVPacket *avpkt)
 {
     const char *ptr = avpkt->data;
     SAMIContext *sami = avctx->priv_data;

libavcodec/srtdec.c

@@ -56,7 +56,7 @@ static int srt_to_ass(AVCodecContext *avctx, AVBPrint *dst,
 }
 
 static int srt_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                            int *got_sub_ptr, AVPacket *avpkt)
+                            int *got_sub_ptr, const AVPacket *avpkt)
 {
     AVBPrint buffer;
     int x1 = -1, y1 = -1, x2 = -1, y2 = -1;

libavcodec/subviewerdec.c

@@ -48,7 +48,7 @@ static int subviewer_event_to_ass(AVBPrint *buf, const char *p)
 }
 
 static int subviewer_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                                  int *got_sub_ptr, AVPacket *avpkt)
+                                  int *got_sub_ptr, const AVPacket *avpkt)
 {
     int ret = 0;
     const char *ptr = avpkt->data;

libavcodec/textdec.c

@@ -46,7 +46,7 @@ static const AVOption options[] = {
 };
 
 static int text_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                             int *got_sub_ptr, AVPacket *avpkt)
+                             int *got_sub_ptr, const AVPacket *avpkt)
 {
     int ret = 0;
     AVBPrint buf;

libavcodec/webvttdec.c

@@ -81,7 +81,7 @@ static int webvtt_event_to_ass(AVBPrint *buf, const char *p)
 }
 
 static int webvtt_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                               int *got_sub_ptr, AVPacket *avpkt)
+                               int *got_sub_ptr, const AVPacket *avpkt)
 {
     int ret = 0;
     const char *ptr = avpkt->data;

libavcodec/xsubdec.c

@@ -48,7 +48,7 @@ static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
 }
 
 static int decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
-                        int *got_sub_ptr, AVPacket *avpkt)
+                        int *got_sub_ptr, const AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;