[xiph-commits] r12205 - trunk/theora/examples

[giles at svn.xiph.org]

Author: giles
Date: 2006-12-11 13:11:32 -0800 (Mon, 11 Dec 2006)
New Revision: 12205

Modified:
   trunk/theora/examples/encoder_example.c
Log:
Generalize the YUV4MPEG stream header parser to allow the tags
to occur in any order. This is allowed by the spec (man page
from the mjpegtools project) and triggered by gstreamer 0.10's
y4menc which uses a different order from what we've previously
seen.

This is still way hacky, but seems to work for old and new files.


Modified: trunk/theora/examples/encoder_example.c
===================================================================
--- trunk/theora/examples/encoder_example.c	2006-12-11 00:42:53 UTC (rev 12204)
+++ trunk/theora/examples/encoder_example.c	2006-12-11 21:11:32 UTC (rev 12205)
@@ -146,7 +146,10 @@
   FILE *test;
   unsigned char buffer[80];
   int ret;
-  int tmp_video_hzn, tmp_video_hzd, tmp_video_an, tmp_video_ad;
+  int tmp_video_hzn = -1,
+      tmp_video_hzd = -1,
+      tmp_video_an = -1,
+      tmp_video_ad = -1;
   int extra_hdr_bytes;
 
   /* open it, look for magic */
@@ -252,7 +255,8 @@
   if(!memcmp(buffer,"YUV4",4)){
     /* possible YUV2MPEG2 format file */
     /* read until newline, or 80 cols, whichever happens first */
-    int i;
+    /* NB the mjpegtools spec doesn't define a length limit */
+    int i,j;
     for(i=0;i<79;i++){
       ret=fread(buffer+i,1,1,test);
       if(ret<1)goto yuv_err;
@@ -264,7 +268,7 @@
     buffer[i]='\0';
 
     if(!memcmp(buffer,"MPEG",4)){
-      char interlace;
+      char interlace = '?';
 
       if(video){
         /* umm, we already have one */
@@ -276,13 +280,52 @@
         fprintf(stderr,"Incorrect YUV input file version; YUV4MPEG2 required.\n");
       }
 
-      ret=sscanf((char *)buffer,"MPEG2 W%d H%d F%d:%d I%c A%d:%d",
-                 &frame_x,&frame_y,&tmp_video_hzn,&tmp_video_hzd,&interlace,
-                 &tmp_video_an,&tmp_video_ad);
-      if(ret<7){
-        fprintf(stderr,"Error parsing YUV4MPEG2 header in file %s.\n",f);
+      /* parse the frame header */
+      j = 5;
+      while (j < i) {
+        if ((buffer[j] != ' ') && (buffer[j-1] == ' ')) 
+          switch (buffer[j]) {
+            case 'W': frame_x = atoi((char*)&buffer[j+1]); break;
+            case 'H': frame_y = atoi((char*)&buffer[j+1]); break;
+            case 'C': /* chroma subsampling */ break;
+            case 'I': interlace = buffer[j+1]; break;
+            case 'F': /* frame rate ratio */
+              tmp_video_hzn = atoi((char*)&buffer[j+1]);
+	      while ((buffer[j] != ':') && (j < i)) j++;
+              tmp_video_hzd = atoi((char*)&buffer[j+1]);
+              break;
+            case 'A': /* sample aspect ratio */
+              tmp_video_an = atoi((char*)&buffer[j+1]);
+	      while ((buffer[j] != ':') && (j < i)) j++;
+              tmp_video_ad = atoi((char*)&buffer[j+1]);
+              break;
+            case 'X': /* metadata */ break;
+            default:
+              fprintf(stderr, "unrecognized stream header tag '%c'\n", buffer[j]);
+              break;
+          }
+        j++;
+      }
+      /* verify data from the stream header */
+      if (frame_x <= 0) {
+        fprintf(stderr,"Error parsing YUV4MPEG2 header:"
+                " missing width tag in file %s.\n", f);
         exit(1);
       }
+      if (frame_y <= 0) {
+        fprintf(stderr,"Error parsing YUV4MPEG2 header:"
+                " missing height tag in file %s.\n", f);
+        exit(1);
+      }
+      if (tmp_video_hzn < 0 || tmp_video_hzd < 0) {
+	/* default to 30 fps */
+	tmp_video_hzn = 30; tmp_video_hzd = 1;
+        fprintf(stderr,"Warning: no framerate defined in file %s.\n", f);
+      }
+      if (tmp_video_an < 0 || tmp_video_ad < 0) {
+	/* default to unknown */
+	tmp_video_an = 0; tmp_video_ad = 0;
+      }
 
       /* update fps and aspect ratio globals if not specified in the command line */
       if (video_hzn==-1) video_hzn = tmp_video_hzn;
@@ -290,7 +333,11 @@
       if (video_an==-1) video_an = tmp_video_an;
       if (video_ad==-1) video_ad = tmp_video_ad;
 
-      if(interlace!='p'){
+      if(interlace=='?'){
+        fprintf(stderr,"Warning: input video isn't marked for interlacing;"
+          " treating this\nas progressive scan video."
+          " Deinterlace first if you get poor results.\n");
+      }else if(interlace!='p'){
         fprintf(stderr,"Input video is interlaced; Theora handles only progressive scan\n");
         exit(1);
       }