packetizer: add isavcC helper

modules/codec/mft.c

@@ -992,7 +992,7 @@ static int InitializeMFT(decoder_t *p_dec)
             int buf_size = p_dec->fmt_in.i_extra + 20;
             uint32_t size = p_dec->fmt_in.i_extra;
             uint8_t *buf = malloc(buf_size);
-            if (((uint8_t*)p_dec->fmt_in.p_extra)[0] == 1)
+            if (h264_isavcC((uint8_t*)p_dec->fmt_in.p_extra, p_dec->fmt_in.i_extra))
             {
                 h264_avcC_to_AnnexB_NAL(p_dec, p_dec->fmt_in.p_extra, p_dec->fmt_in.i_extra,
                                 buf, buf_size,

modules/codec/omxil/mediacodec.c

@@ -313,7 +313,7 @@ static int ParseVideoExtra(decoder_t *p_dec, uint8_t *p_extra, int i_extra)
 
         if (p_dec->fmt_in.i_codec == VLC_CODEC_H264)
         {
-            if (p_extra[0] == 1
+            if ( h264_isavcC(p_extra, i_extra)
              && h264_avcC_to_AnnexB_NAL(p_dec, p_extra, i_extra,
                                 p_buf, buf_size, &size,
                                 &p_sys->u.video.i_nal_length_size) == VLC_SUCCESS)

modules/packetizer/h264_nal.c

@@ -31,6 +31,15 @@
 
 static const uint8_t annexb_startcode[] = { 0x00, 0x00, 0x01 };
 
+bool h264_isavcC( const uint8_t *p_buf, size_t i_buf )
+{
+    return ( i_buf > H264_MIN_AVCC_SIZE &&
+             p_buf[0] == 0x01 &&
+            (p_buf[4] & 0xFC) == 0xFC &&
+            (p_buf[4] & 0x03) != 0x02 &&
+            (p_buf[5] & 0xE0) == 0xE0 );
+}
+
 static inline bool strip_AnnexB_startcode( const uint8_t **pp_data, size_t *pi_data )
 {
     const uint8_t *p_data = *pp_data;

modules/packetizer/h264_nal.h

@@ -113,6 +113,10 @@ struct h264_nal_pps
     avcC: AVCDecoderConfigurationRecord combining SPS & PPS in AVC Sample Format
 */
 
+#define H264_MIN_AVCC_SIZE 7
+
+bool h264_isavcC( const uint8_t *, size_t );
+
 /* Convert AVC Sample format to Annex B in-place */
 void h264_AVC_to_AnnexB( uint8_t *p_buf, uint32_t i_len,
                          uint8_t i_nal_length_size );