stream_lavf: allow setting AVOptions with --stream-lavf-o

This commit also creates a private option struct for stream_lavf.c, but
since I'm lazy, I'm not moving any existing options to it.

DOCS/man/options.rst

@@ -1706,6 +1706,13 @@ OPTIONS
     Same as ``--stream-capture``, but do not start playback. Instead, the entire
     file is dumped.
 
+``--stream-lavf-o=opt1=value1,opt2=value2,...``
+    Set AVOptions on streams opened with libavformat. Unknown or misspelled
+    options are silently ignored. (They are mentioned in the terminal output
+    in verbose mode, i.e. ``--v``. In general we can't print errors, because
+    other options such as e.g. user agent are not available with all protocols,
+    and printing errors for unknown options would end up being too noisy.)
+
 ``--playlist=<filename>``
     Play files according to a playlist file (Supports some common formats.If
     no format is detected, t will be treated as list of files, separated by

common/av_common.c

@@ -19,6 +19,7 @@
 
 #include <libavutil/common.h>
 #include <libavutil/log.h>
+#include <libavutil/dict.h>
 #include <libavcodec/avcodec.h>
 
 #include "common/common.h"
@@ -180,3 +181,11 @@ const char *mp_codec_from_av_codec_id(int codec_id)
     }
     return name;
 }
+
+// kv is in the format as by OPT_KEYVALUELIST(): kv[0]=key0, kv[1]=val0, ...
+// Copy them to the dict.
+void mp_set_avdict(AVDictionary **dict, char **kv)
+{
+    for (int n = 0; kv && kv[n * 2]; n++)
+        av_dict_set(dict, kv[n * 2 + 0], kv[n * 2 + 1], 0);
+}

common/av_common.h

@@ -26,6 +26,7 @@
 
 struct mp_decoder_list;
 struct demux_packet;
+struct AVDictionary;
 
 int mp_lavc_set_extradata(AVCodecContext *avctx, void *ptr, int size);
 void mp_copy_lav_codec_headers(AVCodecContext *avctx, AVCodecContext *st);
@@ -36,5 +37,6 @@ void mp_set_avcodec_threads(AVCodecContext *avctx, int threads);
 void mp_add_lavc_decoders(struct mp_decoder_list *list, enum AVMediaType type);
 int mp_codec_to_av_codec_id(const char *codec);
 const char *mp_codec_from_av_codec_id(int codec_id);
+void mp_set_avdict(struct AVDictionary **dict, char **kv);
 
 #endif

options/options.c

@@ -63,6 +63,7 @@ extern const struct m_sub_options tv_params_conf;
 extern const struct m_sub_options stream_pvr_conf;
 extern const struct m_sub_options stream_cdda_conf;
 extern const struct m_sub_options stream_dvb_conf;
+extern const struct m_sub_options stream_lavf_conf;
 extern const struct m_sub_options sws_conf;
 extern const struct m_sub_options demux_rawaudio_conf;
 extern const struct m_sub_options demux_rawvideo_conf;
@@ -229,6 +230,7 @@ const m_option_t mp_opts[] = {
 #if HAVE_DVBIN
     OPT_SUBSTRUCT("dvbin", stream_dvb_opts, stream_dvb_conf, 0),
 #endif
+    OPT_SUBSTRUCT("", stream_lavf_opts, stream_lavf_conf, 0),
 
 // ------------------------- a-v sync options --------------------
 

options/options.h

@@ -250,6 +250,7 @@ typedef struct MPOpts {
     struct pvr_params *stream_pvr_opts;
     struct cdda_params *stream_cdda_opts;
     struct dvb_params *stream_dvb_opts;
+    struct stream_lavf_params *stream_lavf_opts;
 
     char *cdrom_device;
     int dvd_title;

stream/stream_lavf.c

@@ -25,6 +25,7 @@
 #include "options/path.h"
 #include "common/msg.h"
 #include "common/tags.h"
+#include "common/av_common.h"
 #include "stream.h"
 #include "options/m_option.h"
 
@@ -33,6 +34,21 @@
 #include "bstr/bstr.h"
 #include "talloc.h"
 
+struct stream_lavf_params *stream_lavf_opts;
+
+#define OPT_BASE_STRUCT struct stream_lavf_params
+struct stream_lavf_params {
+    char **avopts;
+};
+
+const struct m_sub_options stream_lavf_conf = {
+    .opts = (const m_option_t[]) {
+        OPT_KEYVALUELIST("stream-lavf-o", avopts, 0),
+        {0}
+    },
+    .size = sizeof(struct stream_lavf_params),
+};
+
 static int open_f(stream_t *stream);
 static struct mp_tags *read_icy(stream_t *stream);
 
@@ -199,6 +215,7 @@ static int open_f(stream_t *stream)
     if (strlen(cust_headers))
         av_dict_set(&dict, "headers", cust_headers, 0);
     av_dict_set(&dict, "icy", "1", 0);
+    mp_set_avdict(&dict, opts->stream_lavf_opts->avopts);
 
     AVIOInterruptCB cb = {
         .callback = interrupt_cb,