h264_mp4toannexb_bsf: factor out extradata parsing

libavcodec/h264_mp4toannexb_bsf.c

@@ -58,37 +58,17 @@ static int alloc_and_copy(uint8_t **poutbuf, int *poutbuf_size,
     return 0;
 }
 
-static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
-                                   AVCodecContext *avctx, const char *args,
-                                   uint8_t **poutbuf, int *poutbuf_size,
-                                   const uint8_t *buf, int buf_size,
-                                   int keyframe)
+static int h264_extradata_to_annexb(AVCodecContext *avctx, const int padding)
 {
-    H264BSFContext *ctx = bsfc->priv_data;
-    uint8_t unit_type;
-    int32_t nal_size;
-    uint32_t cumul_size    = 0;
-    const uint8_t *buf_end = buf + buf_size;
-
-    /* nothing to filter */
-    if (!avctx->extradata || avctx->extradata_size < 6) {
-        *poutbuf      = (uint8_t *)buf;
-        *poutbuf_size = buf_size;
-        return 0;
-    }
-
-    /* retrieve sps and pps NAL units from extradata */
-    if (!ctx->extradata_parsed) {
     uint16_t unit_size;
     uint64_t total_size                 = 0;
     uint8_t *out                        = NULL, unit_nb, sps_done = 0,
              sps_seen                   = 0, pps_seen = 0;
     const uint8_t *extradata            = avctx->extradata + 4;
     static const uint8_t nalu_header[4] = { 0, 0, 0, 1 };
+    int length_size = (*extradata++ & 0x3) + 1; // retrieve length coded size
 
-        /* retrieve length coded size */
-        ctx->length_size = (*extradata++ & 0x3) + 1;
-        if (ctx->length_size == 3)
+    if (length_size == 3)
         return AVERROR(EINVAL);
 
     /* retrieve sps and pps unit(s) */
@@ -108,13 +88,13 @@ static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
 
         unit_size   = AV_RB16(extradata);
         total_size += unit_size + 4;
-            if (total_size > INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE ||
+        if (total_size > INT_MAX - padding ||
             extradata + 2 + unit_size > avctx->extradata +
             avctx->extradata_size) {
             av_free(out);
             return AVERROR(EINVAL);
         }
-            tmp = av_realloc(out, total_size + FF_INPUT_BUFFER_PADDING_SIZE);
+        tmp = av_realloc(out, total_size + padding);
         if (!tmp) {
             av_free(out);
             return AVERROR(ENOMEM);
@@ -147,6 +127,36 @@ static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
     av_free(avctx->extradata);
     avctx->extradata      = out;
     avctx->extradata_size = total_size;
+
+    return length_size;
+}
+
+static int h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
+                                   AVCodecContext *avctx, const char *args,
+                                   uint8_t **poutbuf, int *poutbuf_size,
+                                   const uint8_t *buf, int buf_size,
+                                   int keyframe)
+{
+    H264BSFContext *ctx = bsfc->priv_data;
+    uint8_t unit_type;
+    int32_t nal_size;
+    uint32_t cumul_size    = 0;
+    const uint8_t *buf_end = buf + buf_size;
+    int ret = 0;
+
+    /* nothing to filter */
+    if (!avctx->extradata || avctx->extradata_size < 6) {
+        *poutbuf      = (uint8_t *)buf;
+        *poutbuf_size = buf_size;
+        return 0;
+    }
+
+    /* retrieve sps and pps NAL units from extradata */
+    if (!ctx->extradata_parsed) {
+        ret = h264_extradata_to_annexb(avctx, FF_INPUT_BUFFER_PADDING_SIZE);
+        if (ret < 0)
+            return ret;
+        ctx->length_size      = ret;
         ctx->first_idr        = 1;
         ctx->extradata_parsed = 1;
     }