[FFmpeg-devel] [PATCH] ffmpeg: use AVBPrint API for filter args.

[Clément Bœsch]

---
 ffmpeg.c |   70 ++++++++++++++++++++++++++++----------------------------------
 1 file changed, 32 insertions(+), 38 deletions(-)

diff --git a/ffmpeg.c b/ffmpeg.c
index fad21c0..4a70039 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -807,20 +807,22 @@ static int configure_audio_filters(FilterGraph *fg, AVFilterContext **in_filter,
     AVCodecContext *codec  = ost->st->codec;
     AVCodecContext *icodec = ist->st->codec;
     char *sample_fmts, *sample_rates, *channel_layouts;
-    char args[256];
+    AVBPrint filter_args;
     int ret;
 
+    av_bprint_init(&filter_args, 256, 2048);
+
     avfilter_graph_free(&fg->graph);
     if (!(fg->graph = avfilter_graph_alloc()))
         return AVERROR(ENOMEM);
 
-    snprintf(args, sizeof(args), "time_base=%d/%d:sample_rate=%d:sample_fmt=%s:"
-             "channel_layout=0x%"PRIx64, ist->st->time_base.num,
-             ist->st->time_base.den, icodec->sample_rate,
-             av_get_sample_fmt_name(icodec->sample_fmt), icodec->channel_layout);
+    av_bprintf(&filter_args, "time_base=%d/%d:sample_rate=%d:sample_fmt=%s:"
+               "channel_layout=0x%"PRIx64, ist->st->time_base.num,
+               ist->st->time_base.den, icodec->sample_rate,
+               av_get_sample_fmt_name(icodec->sample_fmt), icodec->channel_layout);
     ret = avfilter_graph_create_filter(&fg->inputs[0]->filter,
                                        avfilter_get_by_name("abuffer"),
-                                       "src", args, NULL, fg->graph);
+                                       "src", filter_args.str, NULL, fg->graph);
     if (ret < 0)
         return ret;
 
@@ -841,19 +843,13 @@ static int configure_audio_filters(FilterGraph *fg, AVFilterContext **in_filter,
     channel_layouts = choose_channel_layouts(ost);
     if (sample_fmts || sample_rates || channel_layouts) {
         AVFilterContext *format;
-        char args[256];
-        int len = 0;
 
-        if (sample_fmts)
-            len += snprintf(args + len, sizeof(args) - len, "sample_fmts=%s:",
-                            sample_fmts);
-        if (sample_rates)
-            len += snprintf(args + len, sizeof(args) - len, "sample_rates=%s:",
-                            sample_rates);
-        if (channel_layouts)
-            len += snprintf(args + len, sizeof(args) - len, "channel_layouts=%s:",
-                            channel_layouts);
-        args[len - 1] = 0;
+        av_bprint_clear(&filter_args);
+        if (sample_fmts)     av_bprintf(&filter_args, "sample_fmts=%s:",     sample_fmts);
+        if (sample_rates)    av_bprintf(&filter_args, "sample_rates=%s:",    sample_rates);
+        if (channel_layouts) av_bprintf(&filter_args, "channel_layouts=%s:", channel_layouts);
+        filter_args.len--;
+        filter_args.str[filter_args.len] = 0;
 
         av_freep(&sample_fmts);
         av_freep(&sample_rates);
@@ -861,7 +857,8 @@ static int configure_audio_filters(FilterGraph *fg, AVFilterContext **in_filter,
 
         ret = avfilter_graph_create_filter(&format,
                                            avfilter_get_by_name("aformat"),
-                                           "aformat", args, NULL, fg->graph);
+                                           "aformat", filter_args.str,
+                                           NULL, fg->graph);
         if (ret < 0)
             return ret;
 
@@ -872,15 +869,16 @@ static int configure_audio_filters(FilterGraph *fg, AVFilterContext **in_filter,
         *out_filter = format;
     }
 
-#define AUTO_INSERT_FILTER(opt_name, filter_name, arg) do {                 \
+#define AUTO_INSERT_FILTER(opt_name, filter_name) do {                      \
     AVFilterContext *filt_ctx;                                              \
                                                                             \
     av_log(NULL, AV_LOG_INFO, opt_name " is forwarded to lavfi "            \
-           "similarly to -af " filter_name "=%s.\n", arg);                  \
+           "similarly to -af " filter_name "=%s.\n", filter_args.str);      \
                                                                             \
     ret = avfilter_graph_create_filter(&filt_ctx,                           \
                                        avfilter_get_by_name(filter_name),   \
-                                       filter_name, arg, NULL, fg->graph);  \
+                                       filter_name, filter_args.str,        \
+                                       NULL, fg->graph);                    \
     if (ret < 0)                                                            \
         return ret;                                                         \
                                                                             \
@@ -892,36 +890,32 @@ static int configure_audio_filters(FilterGraph *fg, AVFilterContext **in_filter,
 } while (0)
 
     if (audio_sync_method > 0) {
-        char args[256] = {0};
-
-        av_strlcatf(args, sizeof(args), "min_comp=0.001:min_hard_comp=%f", audio_drift_threshold);
+        av_bprint_clear(&filter_args);
+        av_bprintf(&filter_args, "min_comp=0.001:min_hard_comp=%f", audio_drift_threshold);
         if (audio_sync_method > 1)
-            av_strlcatf(args, sizeof(args), ":max_soft_comp=%f", audio_sync_method/(double)icodec->sample_rate);
-        AUTO_INSERT_FILTER("-async", "aresample", args);
+            av_bprintf(&filter_args, ":max_soft_comp=%f", audio_sync_method/(double)icodec->sample_rate);
+        AUTO_INSERT_FILTER("-async", "aresample");
     }
 
     if (ost->audio_channels_mapped) {
         int i;
-        AVBPrint pan_buf;
 
-        av_bprint_init(&pan_buf, 256, 8192);
-        av_bprintf(&pan_buf, "0x%"PRIx64,
+        av_bprint_clear(&filter_args);
+        av_bprintf(&filter_args, "0x%"PRIx64,
                    av_get_default_channel_layout(ost->audio_channels_mapped));
         for (i = 0; i < ost->audio_channels_mapped; i++)
             if (ost->audio_channels_map[i] != -1)
-                av_bprintf(&pan_buf, ":c%d=c%d", i, ost->audio_channels_map[i]);
-
-        AUTO_INSERT_FILTER("-map_channel", "pan", pan_buf.str);
-        av_bprint_finalize(&pan_buf, NULL);
+                av_bprintf(&filter_args, ":c%d=c%d", i, ost->audio_channels_map[i]);
+        AUTO_INSERT_FILTER("-map_channel", "pan");
     }
 
     if (audio_volume != 256) {
-        char args[256];
-
-        snprintf(args, sizeof(args), "%lf", audio_volume / 256.);
-        AUTO_INSERT_FILTER("-vol", "volume", args);
+        av_bprint_clear(&filter_args);
+        av_bprintf(&filter_args, "%lf", audio_volume / 256.);
+        AUTO_INSERT_FILTER("-vol", "volume");
     }
 
+    av_bprint_finalize(&filter_args, NULL);
     return 0;
 }
 
-- 
1.7.10.2