[FFmpeg-devel] [PATCH] ffmpeg options: Enable trailing ? for map_channel
pkv.stream
pkv.stream at gmail.com
Fri Aug 25 00:10:49 EEST 2017
Thanks a lot Martin !!! all sorted out thanks to your kind help.
I had run fate previously but obviously missed something; so re-run and
it's ok.
I created two tests per your advice testing for a third channel in a
stereo file and then in a 2.1 file.
Instead of CRC, I've used MD5 because the extant mapchan fate tests were
using it.
Updated patch in attachment.
Michael: would that be OK or do you see other changes to make ?
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From 5c3b0fed39b713b19ed53b5704b1fce63b2742ad Mon Sep 17 00:00:00 2001
From: pkviet <pkv.stream at gmail.com>
Date: Tue, 22 Aug 2017 11:30:45 +0200
Subject: [PATCH] ffmpeg options: Enable trailing ? for map_channel
The -map option allows for a trailing ? so that an error is not thrown if
the input stream does not exist.
This capability is extended to the map_channel option.
This allows a ffmpeg command not to break if an input channel does not
exist, which can be of use (for instance, scripts processing audio
channels with sources having unset number of audio channels).
---
doc/ffmpeg.texi | 13 ++++++++++++-
ffmpeg_opt.c | 21 ++++++++++++++++++---
tests/fate/ffmpeg.mak | 8 ++++++++
tests/ref/fate/mapchan-2ch-extract-ch0-ch2-trailing | 1 +
tests/ref/fate/mapchan-3ch-extract-ch0-ch2-trailing | 1 +
5 files changed, 40 insertions(+), 4 deletions(-)
create mode 100644 tests/ref/fate/mapchan-2ch-extract-ch0-ch2-trailing
create mode 100644 tests/ref/fate/mapchan-3ch-extract-ch0-ch2-trailing
diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
index 4616a42..de6d3f1 100644
--- a/doc/ffmpeg.texi
+++ b/doc/ffmpeg.texi
@@ -996,7 +996,7 @@ such streams is attempted.
Allow input streams with unknown type to be copied instead of failing if copying
such streams is attempted.
- at item -map_channel [@var{input_file_id}. at var{stream_specifier}. at var{channel_id}|-1][:@var{output_file_id}. at var{stream_specifier}]
+ at item -map_channel [@var{input_file_id}. at var{stream_specifier}. at var{channel_id}|-1][?][:@var{output_file_id}. at var{stream_specifier}]
Map an audio channel from a given input to an output. If
@var{output_file_id}. at var{stream_specifier} is not set, the audio channel will
be mapped on all the audio streams.
@@ -1005,6 +1005,10 @@ Using "-1" instead of
@var{input_file_id}. at var{stream_specifier}. at var{channel_id} will map a muted
channel.
+A trailing @code{?} will allow the map_channel to be
+optional: if the map_channel matches no channel the map_channel will be ignored instead
+of failing.
+
For example, assuming @var{INPUT} is a stereo audio file, you can switch the
two audio channels with the following command:
@example
@@ -1052,6 +1056,13 @@ video stream), you can use the following command:
ffmpeg -i input.mkv -filter_complex "[0:1] [0:2] amerge" -c:a pcm_s16le -c:v copy output.mkv
@end example
+To map the first two audio channels from the first input, and using the
+trailing @code{?}, ignore the audio channel mapping if the first input is
+mono instead of stereo:
+ at example
+ffmpeg -i INPUT -map_channel 0.0.0 -map_channel 0.0.1? OUTPUT
+ at end example
+
@item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
Set metadata information of the next output file from @var{infile}. Note that
those are file indices (zero-based), not filenames.
diff --git a/ffmpeg_opt.c b/ffmpeg_opt.c
index 1c4a11e..2f6bfc9 100644
--- a/ffmpeg_opt.c
+++ b/ffmpeg_opt.c
@@ -405,6 +405,11 @@ static int opt_map_channel(void *optctx, const char *opt, const char *arg)
int n;
AVStream *st;
AudioChannelMap *m;
+ char *allow_unused;
+ char *mapchan;
+ mapchan = av_strdup(arg);
+ if (!mapchan)
+ return AVERROR(ENOMEM);
GROW_ARRAY(o->audio_channel_maps, o->nb_audio_channel_maps);
m = &o->audio_channel_maps[o->nb_audio_channel_maps - 1];
@@ -450,10 +455,20 @@ static int opt_map_channel(void *optctx, const char *opt, const char *arg)
m->file_idx, m->stream_idx);
exit_program(1);
}
+ /* allow trailing ? to map_channel */
+ if (allow_unused = strchr(mapchan, '?'))
+ *allow_unused = 0;
if (m->channel_idx < 0 || m->channel_idx >= st->codecpar->channels) {
- av_log(NULL, AV_LOG_FATAL, "mapchan: invalid audio channel #%d.%d.%d\n",
- m->file_idx, m->stream_idx, m->channel_idx);
- exit_program(1);
+ if (allow_unused) {
+ av_log(NULL, AV_LOG_VERBOSE, "mapchan: invalid audio channel #%d.%d.%d\n",
+ m->file_idx, m->stream_idx, m->channel_idx);
+ } else {
+ av_log(NULL, AV_LOG_FATAL, "mapchan: invalid audio channel #%d.%d.%d\n"
+ "To ignore this, add a trailing '?' to the map_channel.\n",
+ m->file_idx, m->stream_idx, m->channel_idx);
+ exit_program(1);
+ }
+
}
return 0;
}
diff --git a/tests/fate/ffmpeg.mak b/tests/fate/ffmpeg.mak
index 0ec5a34..f3fbc84 100644
--- a/tests/fate/ffmpeg.mak
+++ b/tests/fate/ffmpeg.mak
@@ -10,6 +10,14 @@ FATE_MAPCHAN-$(CONFIG_CHANNELMAP_FILTER) += fate-mapchan-silent-mono
fate-mapchan-silent-mono: tests/data/asynth-22050-1.wav
fate-mapchan-silent-mono: CMD = md5 -i $(TARGET_PATH)/tests/data/asynth-22050-1.wav -map_channel -1 -map_channel 0.0.0 -fflags +bitexact -f wav
+FATE_MAPCHAN-$(CONFIG_CHANNELMAP_FILTER) += fate-mapchan-2ch-extract-ch0-ch2-trailing
+fate-mapchan-2ch-extract-ch0-ch2-trailing: tests/data/asynth-44100-2.wav
+fate-mapchan-2ch-extract-ch0-ch2-trailing: CMD = md5 -i $(TARGET_PATH)/tests/data/asynth-44100-2.wav -map_channel 0.0.0 -map_channel 0.0.2? -fflags +bitexact -f wav
+
+FATE_MAPCHAN-$(CONFIG_CHANNELMAP_FILTER) += fate-mapchan-3ch-extract-ch0-ch2-trailing
+fate-mapchan-3ch-extract-ch0-ch2-trailing: tests/data/asynth-44100-3.wav
+fate-mapchan-3ch-extract-ch0-ch2-trailing: CMD = md5 -i $(TARGET_PATH)/tests/data/asynth-44100-3.wav -map_channel 0.0.0 -map_channel 0.0.2? -fflags +bitexact -f wav
+
FATE_MAPCHAN = $(FATE_MAPCHAN-yes)
FATE_FFMPEG += $(FATE_MAPCHAN)
diff --git a/tests/ref/fate/mapchan-2ch-extract-ch0-ch2-trailing b/tests/ref/fate/mapchan-2ch-extract-ch0-ch2-trailing
new file mode 100644
index 0000000..a540037
--- /dev/null
+++ b/tests/ref/fate/mapchan-2ch-extract-ch0-ch2-trailing
@@ -0,0 +1 @@
+b6e1d142b4e484221562e7b66b9bbbdc
diff --git a/tests/ref/fate/mapchan-3ch-extract-ch0-ch2-trailing b/tests/ref/fate/mapchan-3ch-extract-ch0-ch2-trailing
new file mode 100644
index 0000000..6237a98
--- /dev/null
+++ b/tests/ref/fate/mapchan-3ch-extract-ch0-ch2-trailing
@@ -0,0 +1 @@
+ae533985186cab287309c04f6b3e866c
--
2.10.1.windows.1
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