[FFmpeg-devel] [PATCH] ffmpeg: implement input file stream disabling

[Gyan]

At Michael's suggestion, this patch lets -vn/-an/-sn/-dn work for input 
files. Individual streams can still be let through e.g.

     ffmpeg -an -discard:a:1 none -i file ...

will let (only) the 2nd audio stream be seen during stream selection and 
filtergraph construction.

Thanks,
Gyan
-------------- next part --------------
From 9823a71f2055f2c4c4484536291bbd2afee36a81 Mon Sep 17 00:00:00 2001
From: Gyan Doshi <ffmpeg at gyani.pro>
Date: Mon, 10 Dec 2018 20:38:20 +0530
Subject: [PATCH] ffmpeg: implement input file stream disabling

-vn/-an/-sn/-dn can be set to stop processing of streams
of said type from an input file.
---
 fftools/ffmpeg_filter.c |  7 +++++++
 fftools/ffmpeg_opt.c    | 17 +++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
index 6518d50870..8c0ff99dd9 100644
--- a/fftools/ffmpeg_filter.c
+++ b/fftools/ffmpeg_filter.c
@@ -293,10 +293,17 @@ static void init_input_filter(FilterGraph *fg, AVFilterInOut *in)
             exit_program(1);
         }
         ist = input_streams[input_files[file_idx]->ist_index + st->index];
+        if (ist->user_set_discard == AVDISCARD_ALL) {
+            av_log(NULL, AV_LOG_FATAL, "Stream specifier '%s' in filtergraph description %s "
+                   "matches a disabled input stream.\n", p, fg->graph_desc);
+            exit_program(1);
+        }
     } else {
         /* find the first unused stream of corresponding type */
         for (i = 0; i < nb_input_streams; i++) {
             ist = input_streams[i];
+            if (ist->user_set_discard == AVDISCARD_ALL)
+                continue;
             if (ist->dec_ctx->codec_type == type && ist->discard)
                 break;
         }
diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
index d4851a2cd8..59f4236127 100644
--- a/fftools/ffmpeg_opt.c
+++ b/fftools/ffmpeg_opt.c
@@ -746,6 +746,13 @@ static void add_input_streams(OptionsContext *o, AVFormatContext *ic)
 
         MATCH_PER_STREAM_OPT(discard, str, discard_str, ic, st);
         ist->user_set_discard = AVDISCARD_NONE;
+
+        if ((o->video_disable && ist->st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) ||
+            (o->audio_disable && ist->st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) ||
+            (o->subtitle_disable && ist->st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE) ||
+            (o->data_disable && ist->st->codecpar->codec_type == AVMEDIA_TYPE_DATA))
+                ist->user_set_discard = AVDISCARD_ALL;
+
         if (discard_str && av_opt_eval_int(&cc, discard_opt, discard_str, &ist->user_set_discard) < 0) {
             av_log(NULL, AV_LOG_ERROR, "Error parsing discard %s.\n",
                     discard_str);
@@ -2174,6 +2181,8 @@ static int open_output_file(OptionsContext *o, const char *filename)
                 int new_area;
                 ist = input_streams[i];
                 new_area = ist->st->codecpar->width * ist->st->codecpar->height + 100000000*!!ist->st->codec_info_nb_frames;
+                if (ist->user_set_discard == AVDISCARD_ALL)
+                    continue;
                 if((qcr!=MKTAG('A', 'P', 'I', 'C')) && (ist->st->disposition & AV_DISPOSITION_ATTACHED_PIC))
                     new_area = 1;
                 if (ist->st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
@@ -2195,6 +2204,8 @@ static int open_output_file(OptionsContext *o, const char *filename)
                 int score;
                 ist = input_streams[i];
                 score = ist->st->codecpar->channels + 100000000*!!ist->st->codec_info_nb_frames;
+                if (ist->user_set_discard == AVDISCARD_ALL)
+                    continue;
                 if (ist->st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
                     score > best_score) {
                     best_score = score;
@@ -2216,6 +2227,8 @@ static int open_output_file(OptionsContext *o, const char *filename)
                     AVCodec const *output_codec =
                         avcodec_find_encoder(oc->oformat->subtitle_codec);
                     int input_props = 0, output_props = 0;
+                    if (input_streams[i]->user_set_discard == AVDISCARD_ALL)
+                        continue;
                     if (output_codec)
                         output_descriptor = avcodec_descriptor_get(output_codec->id);
                     if (input_descriptor)
@@ -2237,6 +2250,8 @@ static int open_output_file(OptionsContext *o, const char *filename)
         if (!o->data_disable ) {
             enum AVCodecID codec_id = av_guess_codec(oc->oformat, NULL, filename, NULL, AVMEDIA_TYPE_DATA);
             for (i = 0; codec_id != AV_CODEC_ID_NONE && i < nb_input_streams; i++) {
+                if (input_streams[i]->user_set_discard == AVDISCARD_ALL)
+                    continue;
                 if (input_streams[i]->st->codecpar->codec_type == AVMEDIA_TYPE_DATA
                     && input_streams[i]->st->codecpar->codec_id == codec_id )
                     new_data_stream(o, oc, i);
@@ -2275,6 +2290,8 @@ loop_end:
                 int src_idx = input_files[map->file_index]->ist_index + map->stream_index;
 
                 ist = input_streams[input_files[map->file_index]->ist_index + map->stream_index];
+                if (ist->user_set_discard == AVDISCARD_ALL)
+                    continue;
                 if(o->subtitle_disable && ist->st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE)
                     continue;
                 if(o->   audio_disable && ist->st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO)
-- 
2.19.2