From 38a5268dbec56adea750e05c4981f3bbb176e735 Mon Sep 17 00:00:00 2001
From: Henrik Gramner <henrik@gramner.com>
Date: Thu, 7 Jan 2016 01:59:24 +0100
Subject: [PATCH] y4m: Support extended frame headers when seeking

Use the actual length of the frame header of the first frame instead of
assuming a header without extensions when calculating the frame size.

Also makes the frame counter more accurate with extended frame headers.
---
 input/y4m.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/input/y4m.c b/input/y4m.c
index 130ea373..060da0d3 100644
--- a/input/y4m.c
+++ b/input/y4m.c
@@ -64,7 +64,7 @@ static int parse_csp_and_depth( char *csp_name, int *bit_depth )
 
 static int open_file( char *psz_filename, hnd_t *p_handle, video_info_t *info, cli_input_opt_t *opt )
 {
-    y4m_hnd_t *h = malloc( sizeof(y4m_hnd_t) );
+    y4m_hnd_t *h = calloc( 1, sizeof(y4m_hnd_t) );
     int i;
     uint32_t n, d;
     char header[MAX_YUV4_HEADER+10];
@@ -75,7 +75,6 @@ static int open_file( char *psz_filename, hnd_t *p_handle, video_info_t *info, c
     if( !h )
         return -1;
 
-    h->next_frame = 0;
     info->vfr = 0;
 
     if( !strcmp( psz_filename, "-" ) )
@@ -85,8 +84,6 @@ static int open_file( char *psz_filename, hnd_t *p_handle, video_info_t *info, c
     if( h->fh == NULL )
         return -1;
 
-    h->frame_header_len = sizeof(Y4M_FRAME_MAGIC);
-
     /* Read header */
     for( i = 0; i < MAX_YUV4_HEADER; i++ )
     {
@@ -194,7 +191,6 @@ static int open_file( char *psz_filename, hnd_t *p_handle, video_info_t *info, c
     info->thread_safe = 1;
     info->num_frames  = 0;
     info->csp         = colorspace;
-    h->frame_size     = h->frame_header_len;
 
     if( h->bit_depth > 8 )
         info->csp |= X264_CSP_HIGH_DEPTH;
@@ -209,10 +205,18 @@ static int open_file( char *psz_filename, hnd_t *p_handle, video_info_t *info, c
         h->plane_size[i] /= x264_cli_csp_depth_factor( info->csp );
     }
 
-    /* Most common case: frame_header = "FRAME" */
     if( x264_is_regular_file( h->fh ) )
     {
         uint64_t init_pos = ftell( h->fh );
+
+        /* Find out the length of the frame header */
+        int len = 1;
+        while( len <= MAX_FRAME_HEADER && fgetc( h->fh ) != '\n' )
+            len++;
+        FAIL_IF_ERROR( len > MAX_FRAME_HEADER || len < sizeof(Y4M_FRAME_MAGIC), "bad frame header length\n" )
+        h->frame_header_len = len;
+        h->frame_size += len;
+
         fseek( h->fh, 0, SEEK_END );
         uint64_t i_size = ftell( h->fh );
         fseek( h->fh, init_pos, SEEK_SET );
@@ -242,8 +246,6 @@ static int read_frame_internal( cli_pic_t *pic, y4m_hnd_t *h, int bit_depth_uc )
     while( i < MAX_FRAME_HEADER && fgetc( h->fh ) != '\n' )
         i++;
     FAIL_IF_ERROR( i == MAX_FRAME_HEADER, "bad frame header!\n" )
-    h->frame_size = h->frame_size - h->frame_header_len + i+slen+1;
-    h->frame_header_len = i+slen+1;
 
     int error = 0;
     for( i = 0; i < pic->img.planes && !error; i++ )
-- 
2.39.2