rawdec: Allow overriding top field first.

Iam not sure this is the best way to implement it, but its the simplest
and keeps the code seperate from the application. Keeping ffmpeg.c
simple and not requireing user apps to duplicate this code.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffmpeg.c

@@ -2979,6 +2979,7 @@ static int opt_qscale(const char *opt, const char *arg)
 static int opt_top_field_first(const char *opt, const char *arg)
 {
     top_field_first = parse_number_or_die(opt, arg, OPT_INT, 0, 1);
+    opt_default(opt, arg);
     return 0;
 }
 

libavcodec/rawdec.c

@@ -29,15 +29,24 @@
 #include "raw.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
 
 typedef struct RawVideoContext {
+    AVClass *av_class;
     uint32_t palette[AVPALETTE_COUNT];
     unsigned char * buffer;  /* block of memory for holding one frame */
     int             length;  /* number of bytes in buffer */
     int flip;
     AVFrame pic;             ///< AVCodecContext.coded_frame
+    int tff;
 } RawVideoContext;
 
+static const AVOption options[]={
+{"top", "top field first", offsetof(RawVideoContext, tff), FF_OPT_TYPE_INT, {.dbl = -1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM|AV_OPT_FLAG_VIDEO_PARAM},
+{NULL}
+};
+static const AVClass class = { "rawdec", NULL, options, LIBAVUTIL_VERSION_INT };
+
 static const PixelFormatTag pix_fmt_bps_avi[] = {
     { PIX_FMT_MONOWHITE, 1 },
     { PIX_FMT_PAL8,    2 },
@@ -130,6 +139,11 @@ static int raw_decode(AVCodecContext *avctx,
     frame->pkt_pts          = avctx->pkt->pts;
     frame->pkt_pos          = avctx->pkt->pos;
 
+    if(context->tff>=0){
+        frame->interlaced_frame = 1;
+        frame->top_field_first  = context->tff;
+    }
+
     //2bpp and 4bpp raw in avi and mov (yes this is ugly ...)
     if (context->buffer) {
         int i;
@@ -214,4 +228,5 @@ AVCodec ff_rawvideo_decoder = {
     raw_close_decoder,
     raw_decode,
     .long_name = NULL_IF_CONFIG_SMALL("raw video"),
+    .priv_class= &class,
 };