[FFmpeg-devel] [PATCH 2/2] ffmpeg: accept + prefix to -pix_fmt option to disable automatic conversions.

[Nicolas George]

Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
---
 Changelog       |    1 +
 doc/ffmpeg.texi |    8 ++++++++
 ffmpeg.c        |   19 +++++++++++++++++++
 3 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/Changelog b/Changelog
index 47e2981..1b6c688 100644
--- a/Changelog
+++ b/Changelog
@@ -27,6 +27,7 @@ version next:
 - ffmpeg -benchmark_all option
 - super2xsai filter ported from libmpcodecs
 - add libavresample audio conversion library for compatibility
+- accept + prefix to -pix_fmt option to disable automatic conversions.
 
 
 version 0.10:
diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
index e14885c..45b662e 100644
--- a/doc/ffmpeg.texi
+++ b/doc/ffmpeg.texi
@@ -418,6 +418,14 @@ also sources and sinks).  This is an alias for @code{-filter:v}.
 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
 Set pixel format. Use @code{-pix_fmts} to show all the supported
 pixel formats.
+If the selected pixel format can not be selected, ffmpeg will print a
+warning and select the best pixel format supported by the encoder.
+If @var{pix_fmt} is prefixed by a @code{+}, ffmpeg will exit with an error
+if the requested pixel format can not be selected, and automatic conversions
+inside filter graphs are disabled.
+If @var{pix_fmt} is a single @code{+}, ffmpeg selects the same pixel format
+as the input (or graph output) and automatic conversions are disabled.
+
 @item -sws_flags @var{flags} (@emph{input/output})
 Set SwScaler flags.
 @item -vdt @var{n}
diff --git a/ffmpeg.c b/ffmpeg.c
index 6efa12c..e9e899b 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -320,6 +320,7 @@ typedef struct OutputStream {
     int copy_initial_nonkeyframes;
 
     enum PixelFormat pix_fmts[2];
+    int keep_pix_fmt;
 } OutputStream;
 
 
@@ -706,6 +707,15 @@ static enum PixelFormat choose_pixel_fmt(AVStream *st, AVCodec *codec, enum Pixe
 
 static const enum PixelFormat *choose_pixel_fmts(OutputStream *ost)
 {
+    if (ost->keep_pix_fmt) {
+        if (ost->filter)
+            avfilter_graph_disable_auto_convert(ost->filter->graph->graph,
+                                                AVFILTER_DISABLE_CONVERT_ALL);
+        if (ost->st->codec->pix_fmt == PIX_FMT_NONE)
+            return NULL;
+        ost->pix_fmts[0] = ost->st->codec->pix_fmt;
+        return ost->pix_fmts;
+    }
     if (ost->st->codec->pix_fmt != PIX_FMT_NONE) {
         ost->pix_fmts[0] = choose_pixel_fmt(ost->st, ost->enc, ost->st->codec->pix_fmt);
         return ost->pix_fmts;
@@ -808,6 +818,10 @@ static int configure_video_filters(FilterGraph *fg)
             return ret;
     }
 
+    if (ost->keep_pix_fmt)
+        avfilter_graph_disable_auto_convert(fg->graph,
+                                            AVFILTER_DISABLE_CONVERT_ALL);
+
     if ((ret = avfilter_graph_config(fg->graph, NULL)) < 0)
         return ret;
 
@@ -4621,6 +4635,11 @@ static OutputStream *new_video_stream(OptionsContext *o, AVFormatContext *oc, in
 
         video_enc->bits_per_raw_sample = frame_bits_per_raw_sample;
         MATCH_PER_STREAM_OPT(frame_pix_fmts, str, frame_pix_fmt, oc, st);
+        if (frame_pix_fmt && *frame_pix_fmt == '+') {
+            ost->keep_pix_fmt = 1;
+            if (!*++frame_pix_fmt)
+                frame_pix_fmt = NULL;
+        }
         if (frame_pix_fmt && (video_enc->pix_fmt = av_get_pix_fmt(frame_pix_fmt)) == PIX_FMT_NONE) {
             av_log(NULL, AV_LOG_FATAL, "Unknown pixel format requested: %s.\n", frame_pix_fmt);
             exit_program(1);
-- 
1.7.2.5