[FFmpeg] Add .dsf to extension list (DSD support)

+ resample to a lower sample rate if needed, as some variants of DSD
exceed the 524kHz we support internally -- and the 384kHz limit of at
least some outputs (pulse).

Fixes cmus#796.

ip/ffmpeg.c

@@ -141,6 +141,7 @@ static int ffmpeg_open(struct input_plugin_data *ip_data)
 	int err = 0;
 	int i;
 	int stream_index = -1;
+	int out_sample_rate;
 	AVCodec const *codec;
 	AVCodecContext *cc = NULL;
 	AVFormatContext *ic = NULL;
@@ -237,6 +238,7 @@ static int ffmpeg_open(struct input_plugin_data *ip_data)
 	priv->output = ffmpeg_output_create();
 
 	/* Prepare for resampling. */
+	out_sample_rate = min_u(cc->sample_rate, 384000);
 	swr = swr_alloc();
 #if LIBAVCODEC_VERSION_MAJOR >= 60
 	if (cc->ch_layout.order == AV_CHANNEL_ORDER_UNSPEC)
@@ -248,15 +250,15 @@ static int ffmpeg_open(struct input_plugin_data *ip_data)
 	av_opt_set_int(swr, "out_channel_layout", av_get_default_channel_layout(cc->channels), 0);
 #endif
 	av_opt_set_int(swr, "in_sample_rate",     cc->sample_rate, 0);
-	av_opt_set_int(swr, "out_sample_rate",    cc->sample_rate, 0);
+	av_opt_set_int(swr, "out_sample_rate",    out_sample_rate, 0);
 	av_opt_set_sample_fmt(swr, "in_sample_fmt",  cc->sample_fmt, 0);
 	priv->swr = swr;
 
 	ip_data->private = priv;
 #if LIBAVCODEC_VERSION_MAJOR >= 60
-	ip_data->sf = sf_rate(cc->sample_rate) | sf_channels(cc->ch_layout.nb_channels);
+	ip_data->sf = sf_rate(out_sample_rate) | sf_channels(cc->ch_layout.nb_channels);
 #else
-	ip_data->sf = sf_rate(cc->sample_rate) | sf_channels(cc->channels);
+	ip_data->sf = sf_rate(out_sample_rate) | sf_channels(cc->channels);
 #endif
 	switch (cc->sample_fmt) {
 	case AV_SAMPLE_FMT_U8:
@@ -542,9 +544,9 @@ const struct input_plugin_ops ip_ops = {
 
 const int ip_priority = 30;
 const char *const ip_extensions[] = {
-	"aa", "aac", "ac3", "aif", "aifc", "aiff", "ape", "au", "fla", "flac",
-	"m4a", "m4b", "mka", "mkv", "mp+", "mp2", "mp3", "mp4", "mpc", "mpp",
-	"ogg", "opus", "shn", "tak", "tta", "wav", "webm", "wma", "wv",
+	"aa", "aac", "ac3", "aif", "aifc", "aiff", "ape", "au", "dsf", "fla",
+	"flac", "m4a", "m4b", "mka", "mkv", "mp+", "mp2", "mp3", "mp4", "mpc",
+	"mpp", "ogg", "opus", "shn", "tak", "tta", "wav", "webm", "wma", "wv",
 #ifdef USE_FALLBACK_IP
 	"*",
 #endif