ivfdec: support y4m output from raw input

The width and height needed to write the Y4M header can be found by
probing the stream with vpx_codec_peek_stream_info(). This also
has the consequence of supporting multiple codecs from raw files
with automatic detections, should we add additional codecs in the
future.

Change-Id: I7522a8f4c7577b6ed9876d744c59cd86d30c6049

ivfdec.c

@@ -398,6 +398,41 @@ unsigned int file_is_ivf(FILE *infile,
 }
 
 
+unsigned int file_is_raw(FILE *infile,
+                         unsigned int *fourcc,
+                         unsigned int *width,
+                         unsigned int *height,
+                         unsigned int *fps_den,
+                         unsigned int *fps_num)
+{
+    unsigned char buf[32];
+    int is_raw = 0;
+    vpx_codec_stream_info_t si;
+
+    if (fread(buf, 1, 32, infile) == 32)
+    {
+        int i;
+
+        if(mem_get_le32(buf) < 256 * 1024 * 1024)
+            for (i = 0; i < sizeof(ifaces) / sizeof(ifaces[0]); i++)
+                if(!vpx_codec_peek_stream_info(ifaces[i].iface,
+                                               buf + 4, 32 - 4, &si))
+                {
+                    is_raw = 1;
+                    *fourcc = ifaces[i].fourcc;
+                    *width = si.w;
+                    *height = si.h;
+                    *fps_num = 30;
+                    *fps_den = 1;
+                    break;
+                }
+    }
+
+    rewind(infile);
+    return is_raw;
+}
+
+
 static int
 nestegg_read_cb(void *buffer, size_t length, void *userdata)
 {
@@ -688,11 +723,14 @@ int main(int argc, const char **argv_)
         input.kind = IVF_FILE;
     else if(file_is_webm(&input, &fourcc, &width, &height, &fps_den, &fps_num))
         input.kind = WEBM_FILE;
-    else
+    else if(file_is_raw(infile, &fourcc, &width, &height, &fps_den, &fps_num))
         input.kind = RAW_FILE;
-
+    else
-    if (input.kind != RAW_FILE)
     {
+        fprintf(stderr, "Unrecognized input file type.\n");
+        return EXIT_FAILURE;
+    }
+
     if (use_y4m)
     {
         char buffer[128];
@@ -727,12 +765,6 @@ int main(int argc, const char **argv_)
 
             break;
         }
-    }
-    else if(use_y4m)
-    {
-        fprintf(stderr, "YUV4MPEG2 output not supported from raw input.\n");
-        return EXIT_FAILURE;
-    }
 
     if (vpx_codec_dec_init(&decoder, iface ? iface :  ifaces[0].iface, &cfg,
                            postproc ? VPX_CODEC_USE_POSTPROC : 0))