On 17-02-2020 11:07 pm, Fu, Linjie wrote:
-----Original Message-----
From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of
Gyan Doshi
Sent: Tuesday, February 18, 2020 01:33
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH] fftools/ffmpeg_filter: add -autoscale
to disable/enable the default scale
On 17-02-2020 10:57 pm, Fu, Linjie wrote:
-----Original Message-----
From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of
Gyan Doshi
Sent: Tuesday, February 18, 2020 00:53
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH] fftools/ffmpeg_filter: add -
autoscale
to disable/enable the default scale
On 17-02-2020 09:13 pm, Fu, Linjie wrote:
-----Original Message-----
From: Fu, Linjie <linjie...@intel.com>
Sent: Sunday, February 16, 2020 00:13
To: ffmpeg-devel@ffmpeg.org
Cc: Fu, Linjie <linjie...@intel.com>; Eoff, Ullysses A
<ullysses.a.e...@intel.com>
Subject: [PATCH] fftools/ffmpeg_filter: add -autoscale to
disable/enable
the
default scale
Currently, ffmpeg inserts scale filter by default in the filter graph
to force the whole decoded stream to scale into the same size with the
first frame. It's not quite make sense in resolution changing cases if
user wants the rawvideo without any scale.
Using autoscale/noautoscale as an output option to indicate whether
auto
inserting the scale filter in the filter graph:
-noautoscale or -autoscale 0:
disable the default auto scale filter inserting.
ffmpeg -y input.mp4 out1.yuv -noautoscale out2.yuv -autoscale 0
out3.yuv
Update docs.
Signed-off-by: U. Artie Eoff <ullysses.a.e...@intel.com>
Signed-off-by: Linjie Fu <linjie...@intel.com>
---
doc/ffmpeg.texi | 16 ++++++++++++----
fftools/ffmpeg.h | 3 +++
fftools/ffmpeg_filter.c | 2 +-
fftools/ffmpeg_opt.c | 5 +++++
4 files changed, 21 insertions(+), 5 deletions(-)
diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
index 29753f0..aebafb3 100644
--- a/doc/ffmpeg.texi
+++ b/doc/ffmpeg.texi
@@ -734,10 +734,6 @@ ffmpeg -dump_attachment:t "" -i INPUT
Technical note -- attachments are implemented as codec extradata,
so
this
option can actually be used to extract extradata from any stream, not
just
attachments.
-
-@item -noautorotate
-Disable automatically rotating video based on file metadata.
-
@end table
@section Video Options
@@ -819,6 +815,18 @@ Create the filtergraph specified by
@var{filtergraph}
and use it to
filter the stream.
This is an alias for @code{-filter:v}, see the @ref{filter_option,,-filter
option}.
+
+@item -autorotate
+Automatically rotate the video according to file metadata. Enabled by
+default, use @option{-noautorotate} to disable it.
+
+@item -autoscale
+Automatically scale the video according to the resolution of first frame.
+Enabled by default, use @option{-noautoscale} to disable it. When
autoscale is
+disabled, all output frames of filter graph might not be in the same
resolution
+and may be inadequate for some encoder/muxer. Therefore, it is not
recommended
+to disable it unless you really know what you are doing.
+Disable autoscale at your own risk.
@end table
@section Advanced Video options
diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index 7b6f802..8beba6c 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -230,6 +230,8 @@ typedef struct OptionsContext {
int nb_time_bases;
SpecifierOpt *enc_time_bases;
int nb_enc_time_bases;
+ SpecifierOpt *autoscale;
+ int nb_autoscale;
} OptionsContext;
typedef struct InputFilter {
@@ -479,6 +481,7 @@ typedef struct OutputStream {
int force_fps;
int top_field_first;
int rotate_overridden;
+ int autoscale;
double rotate_override_value;
AVRational frame_aspect_ratio;
diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
index 40cc4c1..46c8ea8 100644
--- a/fftools/ffmpeg_filter.c
+++ b/fftools/ffmpeg_filter.c
@@ -469,7 +469,7 @@ static int
configure_output_video_filter(FilterGraph
*fg, OutputFilter *ofilter,
if (ret < 0)
return ret;
- if (ofilter->width || ofilter->height) {
+ if ((ofilter->width || ofilter->height) && ofilter->ost->autoscale) {
char args[255];
AVFilterContext *filter;
AVDictionaryEntry *e = NULL;
diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
index 12d4488..a6f4216 100644
--- a/fftools/ffmpeg_opt.c
+++ b/fftools/ffmpeg_opt.c
@@ -1405,6 +1405,8 @@ static OutputStream
*new_output_stream(OptionsContext *o, AVFormatContext *oc, e
ost->encoder_opts = filter_codec_opts(o->g->codec_opts, ost-
enc-
id, oc, st, ost->enc);
MATCH_PER_STREAM_OPT(presets, str, preset, oc, st);
+ ost->autoscale = 1;
+ MATCH_PER_STREAM_OPT(autoscale, i, ost->autoscale, oc, st);
if (preset && (!(ret = get_preset_file_2(preset, ost->enc->name,
&s))))
{
do {
buf = get_line(s);
@@ -3650,6 +3652,9 @@ const OptionDef options[] = {
{ "autorotate", HAS_ARG | OPT_BOOL | OPT_SPEC |
OPT_EXPERT | OPT_INPUT,
{ .off =
OFFSET(autorotate) },
"automatically insert correct rotate filters" },
+ { "autoscale", HAS_ARG | OPT_BOOL | OPT_SPEC |
+ OPT_EXPERT | OPT_OUTPUT,
{ .off =
OFFSET(autoscale) },
+ "automatically insert a scale filter at the end of the filter graph" },
/* audio options */
{ "aframes", OPT_AUDIO | HAS_ARG | OPT_PERFILE |
OPT_OUTPUT,
{ .func_arg = opt_audio_frames },
--
2.7.4
What happens if user disables autoscale and the frame sizes do vary but
the encoder doesn't support changing props?
That's the point. Currently they would fail without specific notifications for
this usage.
One of the solutions is to declare
AV_CODEC_CAP_VARIABLE_DIMENSIONS capability for encoders [1],
and prompt an error information [2] to indicate " Dynamic resolution
encode is not supported by this encoder."
The further work would be providing dynamic encoding support for some
encoders [3].
So this patch is the first step.
Is this patch intended to be applied first, before the codec flag is
added and checked?
Considering it won't impact the default behavior, IMHO yes it could be.
So, my question still stands. If it is applied tomorrow, and a user
disables autoscale, and ends up feeding frames of varying sizes to, say,
x264 or aom, what happens?
Gyan
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