[MPlayer-dev-eng] [PATCH] libavcodec skip decoding options

[Reimar Döffinger]

Hi,
the attached patch adds support for libavcodecs skip* options, esp.
skiploopfilter can give a big speedup with h264 at little cost.
I need a bit of help with the man page entry though, I'll give the text
here, somebody else please put the formattings in (I don't know
how to make sub-subsections, and no I don't want to learn :-) )

under lavdopts:

skip options
  all these accept a value that specifies when this processing step
  should be skipped:
    none
      never skip
    default
      skip when it is useless (e.g. 0 size packets in AVI)
    nonref
      skip for frames that are not referenced (i.e. not used for decoding
      other frames, the error can not "build up")
    bidir
      skip for B-Frames
    nonkey
      skip for all frames except keyframes
    all
      skip for all frames

  skiploopfilter=<skipvalue> (H.264 only)
    Skips the loop filter (aka deblocking) during H.264 decoding.
    Since the filtered frame is supposed to be used as reference
    for decoding dependant frames this has a worse effect on quality
    than not doing deblocking on e.g. MPEG2 video.
    But at least for high bitrate HDTV this provides a bit speedup with
    no visible quality loss.

  skipidct=<skipvalue> (MPEG1/2 only)
    Skips the IDCT step. This looses a lot of quality in almost all cases.

  skipframe=<skipvalue>
    Skips decoding of frames completely.
    Big speedup, but jerky motion and sometimes bad artefacts.


I intend to apply the code part tomorrow and leave the man page to
whoever will do it *g*

Greetings,
Reimar Döffinger
-------------- next part --------------
Index: libmpcodecs/vd_ffmpeg.c
===================================================================
RCS file: /cvsroot/mplayer/main/libmpcodecs/vd_ffmpeg.c,v
retrieving revision 1.149
diff -u -r1.149 vd_ffmpeg.c
--- libmpcodecs/vd_ffmpeg.c	26 Jun 2005 20:28:12 -0000	1.149
+++ libmpcodecs/vd_ffmpeg.c	15 Jul 2005 09:34:56 -0000
@@ -106,6 +106,11 @@
 static int lavc_param_fast=0;
 static int lavc_param_lowres=0;
 static char *lavc_param_lowres_str=NULL;
+#if LIBAVCODEC_BUILD >= 4758
+static char *lavc_param_skip_loop_filter_str = NULL;
+static char *lavc_param_skip_idct_str = NULL;
+static char *lavc_param_skip_frame_str = NULL;
+#endif
 
 m_option_t lavc_decode_opts_conf[]={
 	{"bug", &lavc_param_workaround_bugs, CONF_TYPE_INT, CONF_RANGE, -1, 999999, NULL},
@@ -122,9 +127,35 @@
         {"fast", &lavc_param_fast, CONF_TYPE_FLAG, 0, 0, CODEC_FLAG2_FAST, NULL},
 #endif
 	{"lowres", &lavc_param_lowres_str, CONF_TYPE_STRING, 0, 0, 0, NULL},
+#if LIBAVCODEC_BUILD >= 4758
+	{"skiploopfilter", &lavc_param_skip_loop_filter_str, CONF_TYPE_STRING, 0, 0, 0, NULL},
+	{"skipidct", &lavc_param_skip_idct_str, CONF_TYPE_STRING, 0, 0, 0, NULL},
+	{"skipframe", &lavc_param_skip_frame_str, CONF_TYPE_STRING, 0, 0, 0, NULL},
+#endif
 	{NULL, NULL, 0, 0, 0, 0, NULL}
 };
 
+#if LIBAVCODEC_BUILD >= 4758
+static enum AVDiscard str2AVDiscard(char *str) {
+  if (!str)
+    return AVDISCARD_DEFAULT;
+  if (strcasecmp(str, "none") == 0)
+    return AVDISCARD_NONE;
+  if (strcasecmp(str, "default") == 0)
+    return AVDISCARD_DEFAULT;
+  if (strcasecmp(str, "nonref") == 0)
+    return AVDISCARD_NONREF;
+  if (strcasecmp(str, "bidir") == 0)
+    return AVDISCARD_BIDIR;
+  if (strcasecmp(str, "nonkey") == 0)
+    return AVDISCARD_NONKEY;
+  if (strcasecmp(str, "all") == 0)
+    return AVDISCARD_ALL;
+  mp_msg(MSGT_DECVIDEO, MSGL_ERR, "Unknown discard value %s\n", str);
+  return AVDISCARD_DEFAULT;
+}
+#endif
+
 // to set/get/query special features/parameters
 static int control(sh_video_t *sh,int cmd,void* arg,...){
     vd_ffmpeg_ctx *ctx = sh->context;
@@ -271,6 +302,11 @@
         avctx->lowres = lavc_param_lowres;
     }
 #endif    
+#if LIBAVCODEC_BUILD >= 4758
+    avctx->skip_loop_filter = str2AVDiscard(lavc_param_skip_loop_filter_str);
+    avctx->skip_idct = str2AVDiscard(lavc_param_skip_idct_str);
+    avctx->skip_frame = str2AVDiscard(lavc_param_skip_frame_str);
+#endif
     mp_dbg(MSGT_DECVIDEO,MSGL_DBG2,"libavcodec.size: %d x %d\n",avctx->width,avctx->height);
     /* AVRn stores huffman table in AVI header */
     /* Pegasus MJPEG stores it also in AVI header, but it uses the common