af: streamline format negotiation

Add dummy input and output filters to remove special cases in the format
negotiation code (af_fix_format_conversion() etc.). The output of the
filter chain is now negotiated in exactly the same way as normal
filters.

Negotiate setting the sample rate in the same way as other audio
parameters. As a side effect, the resampler is inserted at the start of
the filter chain instead of the end, but that shouldn't matter much,
especially since conversion and channel mixing are conflated into the
same filter (due to libavresample's API).

1 files changed, 4 insertions, 6 deletions

diff --git a/audio/decode/dec_audio.c b/audio/decode/dec_audio.c
index 9d0e51629c..c7ae3155ed 100644
--- a/audio/decode/dec_audio.c
+++ b/audio/decode/dec_audio.c
@@ -183,7 +183,7 @@ void uninit_audio(sh_audio_t *sh_audio)
     if (sh_audio->afilter) {
         mp_msg(MSGT_DECAUDIO, MSGL_V, "Uninit audio filters...\n");
         af_uninit(sh_audio->afilter);
-        free(sh_audio->afilter);
+        af_destroy(sh_audio->afilter);
         sh_audio->afilter = NULL;
     }
     if (sh_audio->initialized) {
@@ -202,10 +202,8 @@ int init_audio_filters(sh_audio_t *sh_audio, int in_samplerate,
                        int *out_samplerate, int *out_channels, int *out_format)
 {
     struct af_stream *afs = sh_audio->afilter;
-    if (!afs) {
-        afs = calloc(1, sizeof(struct af_stream));
-        afs->opts = sh_audio->opts;
-    }
+    if (!afs)
+        afs = af_new(sh_audio->opts);
     // input format: same as codec's output format:
     afs->input.rate   = in_samplerate;
     afs->input.nch    = sh_audio->channels;
@@ -230,7 +228,7 @@ int init_audio_filters(sh_audio_t *sh_audio, int in_samplerate,
     // let's autoprobe it!
     if (0 != af_init(afs)) {
         sh_audio->afilter = NULL;
-        free(afs);
+        af_destroy(afs);
         return 0;   // failed :(
     }