remove unneeded length checks

Originally committed as revision 18834 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mxfenc.c

@@ -1308,7 +1308,7 @@ static int mxf_parse_mpeg2_frame(AVFormatContext *s, AVStream *st, AVPacket *pkt
     for(i = 0; i < pkt->size - 4; i++) {
         c = (c<<8) + pkt->data[i];
         if (c == 0x1B5) {
-            if (i + 2 < pkt->size && (pkt->data[i+1] & 0xf0) == 0x10) { // seq ext
+            if ((pkt->data[i+1] & 0xf0) == 0x10) { // seq ext
                 st->codec->profile = pkt->data[i+1] & 0x07;
                 st->codec->level   = pkt->data[i+2] >> 4;
             } else if (i + 5 < pkt->size && (pkt->data[i+1] & 0xf0) == 0x80) { // pict coding ext
@@ -1316,7 +1316,6 @@ static int mxf_parse_mpeg2_frame(AVFormatContext *s, AVStream *st, AVPacket *pkt
                 break;
             }
         } else if (c == 0x1b8) { // gop
-            if (i + 4 < pkt->size) {
                 if (pkt->data[i+4]>>6 & 0x01) // closed
                     *flags |= 0x80; // random access
                 if (!mxf->header_written) {
@@ -1334,10 +1333,8 @@ static int mxf_parse_mpeg2_frame(AVFormatContext *s, AVStream *st, AVPacket *pkt
                     av_log(s, AV_LOG_DEBUG, "frame %d %d:%d:%d%c%d\n", mxf->timecode_start,
                            hours, minutes, seconds, mxf->timecode_drop_frame ? ';':':', frames);
                 }
-            }
         } else if (c == 0x1b3) { // seq
             *flags |= 0x40;
-            if (i + 4 < pkt->size) {
                 switch ((pkt->data[i+4]>>4) & 0xf) {
                 case 2:  sc->aspect_ratio = (AVRational){  4,  3}; break;
                 case 3:  sc->aspect_ratio = (AVRational){ 16,  9}; break;
@@ -1346,7 +1343,6 @@ static int mxf_parse_mpeg2_frame(AVFormatContext *s, AVStream *st, AVPacket *pkt
                     av_reduce(&sc->aspect_ratio.num, &sc->aspect_ratio.den,
                               st->codec->width, st->codec->height, 1024*1024);
                 }
-            }
         } else if (c == 0x100) { // pic
             int pict_type = (pkt->data[i+2]>>3) & 0x07;
             if (pict_type == 2) { // P frame