ad_lavc: expose an option to enable threading

DOCS/man/en/options.rst

@@ -42,6 +42,12 @@ OPTIONS
     requested number of output channels is set with the ``--channels`` option.
     Useful for playing surround audio on a stereo system.
 
+``--ad-lavc-threads=<0-16>``
+    Number of threads to use for decoding. Whether threading is actually
+    supported depends on codec. As of this writing, it's supported for some
+    lossless codecs only. 0 means autodetect number of cores on the
+    machine and use that, up to the maximum of 16 (default: 1).
+
 ``--ad-lavc-o=<key>=<value>[,<key>=<value>[,...]]``
     Pass AVOptions to libavcodec decoder. Note, a patch to make the o=
     unneeded and pass all unknown options through the AVOption system is

audio/decode/ad_lavc.c

@@ -56,6 +56,7 @@ static int decode_new_packet(struct dec_audio *da);
 const m_option_t ad_lavc_decode_opts_conf[] = {
     OPT_FLOATRANGE("ac3drc", ad_lavc_param.ac3drc, 0, 0, 2),
     OPT_FLAG("downmix", ad_lavc_param.downmix, 0),
+    OPT_INTRANGE("threads", ad_lavc_param.threads, 0, 1, 16),
     OPT_STRING("o", ad_lavc_param.avopt, 0),
     {0}
 };
@@ -249,6 +250,8 @@ static int init(struct dec_audio *da, const char *decoder)
     if (sh->lav_headers)
         mp_copy_lav_codec_headers(lavc_context, sh->lav_headers);
 
+    mp_set_avcodec_threads(lavc_context, opts->threads);
+
     /* open it */
     if (avcodec_open2(lavc_context, lavc_codec, NULL) < 0) {
         mp_tmsg(MSGT_DECAUDIO, MSGL_ERR, "Could not open codec.\n");

mpvcore/options.c

@@ -858,6 +858,7 @@ const struct MPOpts mp_default_opts = {
     .ad_lavc_param = {
         .ac3drc = 1.,
         .downmix = 1,
+        .threads = 1,
     },
     .lavfdopts = {
         .allow_mimetype = 1,

mpvcore/options.h

@@ -225,6 +225,7 @@ typedef struct MPOpts {
     struct ad_lavc_param {
         float ac3drc;
         int downmix;
+        int threads;
         char *avopt;
     } ad_lavc_param;