[FFmpeg-devel] [PATCH v1] avcodec/mpeg12dec: switch to AVBufferRef buffer for a53 caption

[lance.lmwang at gmail.com]

From: Limin Wang <lance.lmwang at gmail.com>

Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
---
 libavcodec/mpeg12dec.c | 73 +++++++++++++++++++++++++++-----------------------
 1 file changed, 40 insertions(+), 33 deletions(-)

diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c
index 775579f..86cdebd 100644
--- a/libavcodec/mpeg12dec.c
+++ b/libavcodec/mpeg12dec.c
@@ -57,8 +57,7 @@ typedef struct Mpeg1Context {
     AVPanScan pan_scan;         /* some temporary storage for the panscan */
     AVStereo3D stereo3d;
     int has_stereo3d;
-    uint8_t *a53_caption;
-    int a53_caption_size;
+    AVBufferRef *a53_buf_ref;
     uint8_t afd;
     int has_afd;
     int slice_count;
@@ -1630,13 +1629,13 @@ static int mpeg_field_start(MpegEncContext *s, const uint8_t *buf, int buf_size)
             return AVERROR(ENOMEM);
         memcpy(pan_scan->data, &s1->pan_scan, sizeof(s1->pan_scan));
 
-        if (s1->a53_caption) {
-            AVFrameSideData *sd = av_frame_new_side_data(
+        if (s1->a53_buf_ref) {
+            AVFrameSideData *sd = av_frame_new_side_data_from_buf(
                 s->current_picture_ptr->f, AV_FRAME_DATA_A53_CC,
-                s1->a53_caption_size);
-            if (sd)
-                memcpy(sd->data, s1->a53_caption, s1->a53_caption_size);
-            av_freep(&s1->a53_caption);
+                s1->a53_buf_ref);
+            if (!sd)
+                av_buffer_unref(&s1->a53_buf_ref);
+            s1->a53_buf_ref = NULL;
         }
 
         if (s1->has_stereo3d) {
@@ -2238,14 +2237,18 @@ static int mpeg_decode_a53_cc(AVCodecContext *avctx,
         /* extract A53 Part 4 CC data */
         int cc_count = p[5] & 0x1f;
         if (cc_count > 0 && buf_size >= 7 + cc_count * 3) {
-            av_freep(&s1->a53_caption);
-            s1->a53_caption_size = cc_count * 3;
-            s1->a53_caption      = av_malloc(s1->a53_caption_size);
-            if (!s1->a53_caption) {
-                s1->a53_caption_size = 0;
-            } else {
-                memcpy(s1->a53_caption, p + 7, s1->a53_caption_size);
-            }
+            int old_size = s1->a53_buf_ref ? s1->a53_buf_ref->size : 0;
+            const uint64_t new_size = (old_size + cc_count
+                                            * UINT64_C(3));
+            int ret;
+
+            if (new_size > INT_MAX)
+                return AVERROR(EINVAL);
+
+            ret = av_buffer_realloc(&s1->a53_buf_ref, new_size);
+            if (ret >= 0)
+                memcpy(s1->a53_buf_ref->data + old_size, p + 7, cc_count * UINT64_C(3));
+
             avctx->properties |= FF_CODEC_PROPERTY_CLOSED_CAPTIONS;
         }
         return 1;
@@ -2254,19 +2257,21 @@ static int mpeg_decode_a53_cc(AVCodecContext *avctx,
         /* extract SCTE-20 CC data */
         GetBitContext gb;
         int cc_count = 0;
-        int i;
+        int i, ret;
 
         init_get_bits(&gb, p + 2, buf_size - 2);
         cc_count = get_bits(&gb, 5);
         if (cc_count > 0) {
-            av_freep(&s1->a53_caption);
-            s1->a53_caption_size = cc_count * 3;
-            s1->a53_caption      = av_mallocz(s1->a53_caption_size);
-            if (!s1->a53_caption) {
-                s1->a53_caption_size = 0;
-            } else {
+            int old_size = s1->a53_buf_ref ? s1->a53_buf_ref->size : 0;
+            const uint64_t new_size = (old_size + cc_count
+                                            * UINT64_C(3));
+            if (new_size > INT_MAX)
+                return AVERROR(EINVAL);
+
+            ret = av_buffer_realloc(&s1->a53_buf_ref, new_size);
+            if (ret >= 0) {
                 uint8_t field, cc1, cc2;
-                uint8_t *cap = s1->a53_caption;
+                uint8_t *cap = s1->a53_buf_ref->data;
                 for (i = 0; i < cc_count && get_bits_left(&gb) >= 26; i++) {
                     skip_bits(&gb, 2); // priority
                     field = get_bits(&gb, 2);
@@ -2318,21 +2323,23 @@ static int mpeg_decode_a53_cc(AVCodecContext *avctx,
          * on the even field. There also exist DVDs in the wild that encode an odd field count and the
          * caption_extra_field_added/caption_odd_field_first bits change per packet to allow that. */
         int cc_count = 0;
-        int i;
+        int i, ret;
         // There is a caption count field in the data, but it is often
         // incorrect.  So count the number of captions present.
         for (i = 5; i + 6 <= buf_size && ((p[i] & 0xfe) == 0xfe); i += 6)
             cc_count++;
         // Transform the DVD format into A53 Part 4 format
         if (cc_count > 0) {
-            av_freep(&s1->a53_caption);
-            s1->a53_caption_size = cc_count * 6;
-            s1->a53_caption      = av_malloc(s1->a53_caption_size);
-            if (!s1->a53_caption) {
-                s1->a53_caption_size = 0;
-            } else {
+            int old_size = s1->a53_buf_ref ? s1->a53_buf_ref->size : 0;
+            const uint64_t new_size = (old_size + cc_count
+                                            * UINT64_C(6));
+            if (new_size > INT_MAX)
+                return AVERROR(EINVAL);
+
+            ret = av_buffer_realloc(&s1->a53_buf_ref, new_size);
+            if (ret >= 0) {
                 uint8_t field1 = !!(p[4] & 0x80);
-                uint8_t *cap = s1->a53_caption;
+                uint8_t *cap = s1->a53_buf_ref->data;
                 p += 5;
                 for (i = 0; i < cc_count; i++) {
                     cap[0] = (p[0] == 0xff && field1) ? 0xfc : 0xfd;
@@ -2871,7 +2878,7 @@ static av_cold int mpeg_decode_end(AVCodecContext *avctx)
 
     if (s->mpeg_enc_ctx_allocated)
         ff_mpv_common_end(&s->mpeg_enc_ctx);
-    av_freep(&s->a53_caption);
+    av_buffer_unref(&s->a53_buf_ref);
     return 0;
 }
 
-- 
2.6.4