typo fixes

Originally committed as revision 9719 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/imgconvert.c

 /*
- * Misc image convertion routines
+ * Misc image conversion routines
  * Copyright (c) 2001, 2002, 2003 Fabrice Bellard.
  *
  * This file is part of FFmpeg.
@@ -21,7 +21,7 @@
 
 /**
  * @file imgconvert.c
- * Misc image convertion routines.
+ * misc image conversion routines
  */
 
 /* TODO:
@@ -1852,7 +1852,7 @@ typedef struct ConvertEntry {
                     const AVPicture *src, int width, int height);
 } ConvertEntry;
 
-/* Add each new convertion function in this table. In order to be able
+/* Add each new conversion function in this table. In order to be able
    to convert from any format to any format, the following constraints
    must be satisfied:
 

libavcodec/imgconvert_template.h

 /*
- * Templates for image convertion routines
+ * templates for image conversion routines
  * Copyright (c) 2001, 2002, 2003 Fabrice Bellard.
  *
  * This file is part of FFmpeg.

libavcodec/pngdec.c

@@ -72,7 +72,7 @@ static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
 };
 
 /* NOTE: we try to construct a good looking image at each pass. width
-   is the original image width. We also do pixel format convertion at
+   is the original image width. We also do pixel format conversion at
    this stage */
 static void png_put_interlaced_row(uint8_t *dst, int width,
                                    int bits_per_pixel, int pass,

libavcodec/resample.c

 /*
- * Sample rate convertion for both audio and video
+ * samplerate conversion for both audio and video
  * Copyright (c) 2000 Fabrice Bellard.
  *
  * This file is part of FFmpeg.
@@ -21,7 +21,7 @@
 
 /**
  * @file resample.c
- * Sample rate convertion for both audio and video.
+ * samplerate conversion for both audio and video
  */
 
 #include "avcodec.h"

libavformat/grab.c

@@ -212,7 +212,7 @@ static int grab_read_header(AVFormatContext *s1, AVFormatParameters *ap)
             if (aiw_init(s) < 0)
                 goto fail;
             s->aiw_enabled = 1;
-            /* force 420P format because convertion from YUV422 to YUV420P
+            /* force 420P format because conversion from YUV422 to YUV420P
                is done in this driver (ugly) */
             s->frame_format = VIDEO_PALETTE_YUV420P;
         }