diff --git a/cmdutils.c b/cmdutils.c
index 8ef477fd01..2312ca2ac2 100644
--- a/cmdutils.c
+++ b/cmdutils.c
@@ -1094,7 +1094,7 @@ int show_filters(void *optctx, const char *opt, const char *arg)
 
 int show_pix_fmts(void *optctx, const char *opt, const char *arg)
 {
-    enum AVPixelFormat pix_fmt;
+    const AVPixFmtDescriptor *pix_desc = NULL;
 
     printf("Pixel formats:\n"
            "I.... = Supported Input  format for conversion\n"
@@ -1110,8 +1110,8 @@ int show_pix_fmts(void *optctx, const char *opt, const char *arg)
 #   define sws_isSupportedOutput(x) 0
 #endif
 
-    for (pix_fmt = 0; pix_fmt < AV_PIX_FMT_NB; pix_fmt++) {
-        const AVPixFmtDescriptor *pix_desc = &av_pix_fmt_descriptors[pix_fmt];
+    while ((pix_desc = av_pix_fmt_desc_next(pix_desc))) {
+        enum AVPixelFormat pix_fmt = av_pix_fmt_desc_get_id(pix_desc);
         if(!pix_desc->name)
             continue;
         printf("%c%c%c%c%c %-16s       %d            %2d\n",
@@ -1484,13 +1484,19 @@ void *grow_array(void *array, int elem_size, int *size, int new_size)
 
 static int alloc_buffer(FrameBuffer **pool, AVCodecContext *s, FrameBuffer **pbuf)
 {
-    FrameBuffer  *buf = av_mallocz(sizeof(*buf));
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->pix_fmt);
+    FrameBuffer *buf;
     int i, ret;
-    const int pixel_size = av_pix_fmt_descriptors[s->pix_fmt].comp[0].step_minus1+1;
+    int pixel_size;
     int h_chroma_shift, v_chroma_shift;
     int edge = 32; // XXX should be avcodec_get_edge_width(), but that fails on svq1
     int w = s->width, h = s->height;
 
+    if (!desc)
+        return AVERROR(EINVAL);
+    pixel_size = desc->comp[0].step_minus1 + 1;
+
+    buf = av_mallocz(sizeof(*buf));
     if (!buf)
         return AVERROR(ENOMEM);
 
diff --git a/configure b/configure
index a304221b05..cce6aadb8f 100755
--- a/configure
+++ b/configure
@@ -3189,6 +3189,10 @@ case $target_os in
                       -l:drtaeabi.dso -l:scppnwdl.dso -lsupc++ -lgcc \
                       -l:libc.dso -l:libm.dso -l:euser.dso -l:libcrt0.lib
         ;;
+    osf1)
+        add_cppflags -D_OSF_SOURCE -D_POSIX_PII -D_REENTRANT
+        FFSERVERLDFLAGS=
+        ;;
     none)
         ;;
     *)
diff --git a/doc/APIchanges b/doc/APIchanges
index f0f1531215..1d6d34b500 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -97,6 +97,11 @@ API changes, most recent first:
 2012-03-26 - a67d9cf - lavfi 2.66.100
   Add avfilter_fill_frame_from_{audio_,}buffer_ref() functions.
 
+2012-10-12 - xxxxxxx - lavu 51.44.0 - pixdesc.h
+  Add functions for accessing pixel format descriptors.
+  Accessing the av_pix_fmt_descriptors array directly is now
+  deprecated.
+
 2012-10-xx - xxxxxxx - lavu 51.43.0 - aes.h, md5.h, sha.h, tree.h
   Add functions for allocating the opaque contexts for the algorithms,
   deprecate the context size variables.
diff --git a/libavformat/md5enc.c b/libavformat/md5enc.c
index f3653084e7..050efb1513 100644
--- a/libavformat/md5enc.c
+++ b/libavformat/md5enc.c
@@ -23,13 +23,16 @@
 #include "avformat.h"
 #include "internal.h"
 
-#define PRIVSIZE 512
+struct MD5Context {
+    struct AVMD5 *md5;
+};
 
 static void md5_finish(struct AVFormatContext *s, char *buf)
 {
+    struct MD5Context *c = s->priv_data;
     uint8_t md5[16];
     int i, offset = strlen(buf);
-    av_md5_final(s->priv_data, md5);
+    av_md5_final(c->md5, md5);
     for (i = 0; i < sizeof(md5); i++) {
         snprintf(buf + offset, 3, "%02"PRIx8, md5[i]);
         offset += 2;
@@ -44,32 +47,36 @@ static void md5_finish(struct AVFormatContext *s, char *buf)
 #if CONFIG_MD5_MUXER
 static int write_header(struct AVFormatContext *s)
 {
-    if (PRIVSIZE < av_md5_size) {
-        av_log(s, AV_LOG_ERROR, "Insuffient size for md5 context\n");
-        return -1;
-    }
-    av_md5_init(s->priv_data);
+    struct MD5Context *c = s->priv_data;
+    c->md5 = av_md5_alloc();
+    if (!c->md5)
+        return AVERROR(ENOMEM);
+    av_md5_init(c->md5);
     return 0;
 }
 
 static int write_packet(struct AVFormatContext *s, AVPacket *pkt)
 {
-    av_md5_update(s->priv_data, pkt->data, pkt->size);
+    struct MD5Context *c = s->priv_data;
+    av_md5_update(c->md5, pkt->data, pkt->size);
     return 0;
 }
 
 static int write_trailer(struct AVFormatContext *s)
 {
+    struct MD5Context *c = s->priv_data;
     char buf[64] = "MD5=";
 
     md5_finish(s, buf);
+
+    av_freep(&c->md5);
     return 0;
 }
 
 AVOutputFormat ff_md5_muxer = {
     .name              = "md5",
     .long_name         = NULL_IF_CONFIG_SMALL("MD5 testing"),
-    .priv_data_size    = PRIVSIZE,
+    .priv_data_size    = sizeof(struct MD5Context),
     .audio_codec       = AV_CODEC_ID_PCM_S16LE,
     .video_codec       = AV_CODEC_ID_RAWVIDEO,
     .write_header      = write_header,
@@ -80,15 +87,21 @@ AVOutputFormat ff_md5_muxer = {
 #endif
 
 #if CONFIG_FRAMEMD5_MUXER
+static int framemd5_write_header(struct AVFormatContext *s)
+{
+    struct MD5Context *c = s->priv_data;
+    c->md5 = av_md5_alloc();
+    if (!c->md5)
+        return AVERROR(ENOMEM);
+    return ff_framehash_write_header(s);
+}
+
 static int framemd5_write_packet(struct AVFormatContext *s, AVPacket *pkt)
 {
+    struct MD5Context *c = s->priv_data;
     char buf[256];
-    if (PRIVSIZE < av_md5_size) {
-        av_log(s, AV_LOG_ERROR, "Insuffient size for md5 context\n");
-        return -1;
-    }
-    av_md5_init(s->priv_data);
-    av_md5_update(s->priv_data, pkt->data, pkt->size);
+    av_md5_init(c->md5);
+    av_md5_update(c->md5, pkt->data, pkt->size);
 
     snprintf(buf, sizeof(buf) - 64, "%d, %10"PRId64", %10"PRId64", %8d, %8d, ",
              pkt->stream_index, pkt->dts, pkt->pts, pkt->duration, pkt->size);
@@ -96,14 +109,22 @@ static int framemd5_write_packet(struct AVFormatContext *s, AVPacket *pkt)
     return 0;
 }
 
+static int framemd5_write_trailer(struct AVFormatContext *s)
+{
+    struct MD5Context *c = s->priv_data;
+    av_freep(&c->md5);
+    return 0;
+}
+
 AVOutputFormat ff_framemd5_muxer = {
     .name              = "framemd5",
     .long_name         = NULL_IF_CONFIG_SMALL("Per-frame MD5 testing"),
-    .priv_data_size    = PRIVSIZE,
+    .priv_data_size    = sizeof(struct MD5Context),
     .audio_codec       = AV_CODEC_ID_PCM_S16LE,
     .video_codec       = AV_CODEC_ID_RAWVIDEO,
-    .write_header      = ff_framehash_write_header,
+    .write_header      = framemd5_write_header,
     .write_packet      = framemd5_write_packet,
+    .write_trailer     = framemd5_write_trailer,
     .flags             = AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,
 };
 #endif
diff --git a/libavformat/md5proto.c b/libavformat/md5proto.c
index f7c8b78fee..6af0a6ed26 100644
--- a/libavformat/md5proto.c
+++ b/libavformat/md5proto.c
@@ -27,37 +27,41 @@
 #include "avio.h"
 #include "url.h"
 
-#define PRIV_SIZE 128
+struct MD5Context {
+    struct AVMD5 *md5;
+};
 
 static int md5_open(URLContext *h, const char *filename, int flags)
 {
-    if (PRIV_SIZE < av_md5_size) {
-        av_log(NULL, AV_LOG_ERROR, "Insuffient size for MD5 context\n");
-        return -1;
-    }
+    struct MD5Context *c = h->priv_data;
 
     if (!(flags & AVIO_FLAG_WRITE))
         return AVERROR(EINVAL);
 
-    av_md5_init(h->priv_data);
+    c->md5 = av_md5_alloc();
+    if (!c->md5)
+        return AVERROR(ENOMEM);
+    av_md5_init(c->md5);
 
     return 0;
 }
 
 static int md5_write(URLContext *h, const unsigned char *buf, int size)
 {
-    av_md5_update(h->priv_data, buf, size);
+    struct MD5Context *c = h->priv_data;
+    av_md5_update(c->md5, buf, size);
     return size;
 }
 
 static int md5_close(URLContext *h)
 {
+    struct MD5Context *c = h->priv_data;
     const char *filename = h->filename;
     uint8_t md5[16], buf[64];
     URLContext *out;
     int i, err = 0;
 
-    av_md5_final(h->priv_data, md5);
+    av_md5_final(c->md5, md5);
     for (i = 0; i < sizeof(md5); i++)
         snprintf(buf + i*2, 3, "%02x", md5[i]);
     buf[i*2] = '\n';
@@ -76,6 +80,8 @@ static int md5_close(URLContext *h)
             err = AVERROR(errno);
     }
 
+    av_freep(&c->md5);
+
     return err;
 }
 
@@ -85,5 +91,5 @@ URLProtocol ff_md5_protocol = {
     .url_open            = md5_open,
     .url_write           = md5_write,
     .url_close           = md5_close,
-    .priv_data_size      = PRIV_SIZE,
+    .priv_data_size      = sizeof(struct MD5Context),
 };
diff --git a/libavutil/pixdesc.c b/libavutil/pixdesc.c
index 0958718b50..3b5f2643c2 100644
--- a/libavutil/pixdesc.c
+++ b/libavutil/pixdesc.c
@@ -21,6 +21,8 @@
 
 #include <stdio.h>
 #include <string.h>
+
+#include "common.h"
 #include "pixfmt.h"
 #include "pixdesc.h"
 
@@ -122,6 +124,9 @@ void av_write_image_line(const uint16_t *src,
     }
 }
 
+#if !FF_API_PIX_FMT_DESC
+static
+#endif
 const AVPixFmtDescriptor av_pix_fmt_descriptors[AV_PIX_FMT_NB] = {
     [AV_PIX_FMT_YUV420P] = {
         .name = "yuv420p",
@@ -1485,3 +1490,28 @@ char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt
 
     return buf;
 }
+
+const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
+{
+    if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
+        return NULL;
+    return &av_pix_fmt_descriptors[pix_fmt];
+}
+
+const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)
+{
+    if (!prev)
+        return &av_pix_fmt_descriptors[0];
+    if (prev - av_pix_fmt_descriptors < FF_ARRAY_ELEMS(av_pix_fmt_descriptors) - 1)
+        return prev + 1;
+    return NULL;
+}
+
+enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc)
+{
+    if (desc < av_pix_fmt_descriptors ||
+        desc >= av_pix_fmt_descriptors + FF_ARRAY_ELEMS(av_pix_fmt_descriptors))
+        return AV_PIX_FMT_NONE;
+
+    return desc - av_pix_fmt_descriptors;
+}
diff --git a/libavutil/pixdesc.h b/libavutil/pixdesc.h
index 465c215190..ccbee9b2f1 100644
--- a/libavutil/pixdesc.h
+++ b/libavutil/pixdesc.h
@@ -99,10 +99,12 @@ typedef struct AVPixFmtDescriptor{
  */
 #define PIX_FMT_PSEUDOPAL 64
 
+#if FF_API_PIX_FMT_DESC
 /**
  * The array of all the pixel format descriptors.
  */
 extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
+#endif
 
 /**
  * Read a line from an image, and write the values of the
@@ -183,4 +185,25 @@ char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt
  */
 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
 
+/**
+ * @return a pixel format descriptor for provided pixel format or NULL if
+ * this pixel format is unknown.
+ */
+const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt);
+
+/**
+ * Iterate over all pixel format descriptors known to libavutil.
+ *
+ * @param prev previous descriptor. NULL to get the first descriptor.
+ *
+ * @return next descriptor or NULL after the last descriptor
+ */
+const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev);
+
+/**
+ * @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
+ * is not a valid pointer to a pixel format descriptor.
+ */
+enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc);
+
 #endif /* AVUTIL_PIXDESC_H */
diff --git a/libavutil/version.h b/libavutil/version.h
index 6c313e4202..25dd42dd66 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -39,7 +39,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 51
-#define LIBAVUTIL_VERSION_MINOR 75
+#define LIBAVUTIL_VERSION_MINOR 76
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
@@ -87,6 +87,9 @@
 #ifndef FF_API_CONTEXT_SIZE
 #define FF_API_CONTEXT_SIZE             (LIBAVUTIL_VERSION_MAJOR < 52)
 #endif
+#ifndef FF_API_PIX_FMT_DESC
+#define FF_API_PIX_FMT_DESC             (LIBAVUTIL_VERSION_MAJOR < 52)
+#endif
 
 /**
  * @}
diff --git a/tools/graph2dot.c b/tools/graph2dot.c
index c4a50a8278..4a30beb754 100644
--- a/tools/graph2dot.c
+++ b/tools/graph2dot.c
@@ -82,9 +82,10 @@ static void print_digraph(FILE *outfile, AVFilterGraph *graph)
                         link->srcpad->name, link->dstpad->name);
 
                 if (link->type == AVMEDIA_TYPE_VIDEO) {
+                    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
                     fprintf(outfile,
                             "fmt:%s w:%d h:%d tb:%d/%d",
-                            av_pix_fmt_descriptors[link->format].name,
+                            desc->name,
                             link->w, link->h,
                             link->time_base.num, link->time_base.den);
                 } else if (link->type == AVMEDIA_TYPE_AUDIO) {