build: address AVCodec, AVInputFormat, AVOutputFormat const warnings

FFmpeg recently changed these to be const on their side.

audio/decode/ad_lavc.c

@@ -85,7 +85,7 @@ static bool init(struct mp_filter *da, struct mp_codec_params *codec,
     struct ad_lavc_params *opts =
         mp_get_config_group(ctx, da->global, &ad_lavc_conf);
     AVCodecContext *lavc_context;
-    AVCodec *lavc_codec;
+    const AVCodec *lavc_codec;
 
     ctx->codec_timebase = mp_get_codec_timebase(codec);
 

audio/decode/ad_spdif.c

@@ -116,7 +116,7 @@ static void determine_codec_params(struct mp_filter *da, AVPacket *pkt,
     if (profile != FF_PROFILE_UNKNOWN || spdif_ctx->codec_id != AV_CODEC_ID_DTS)
         return;
 
-    AVCodec *codec = avcodec_find_decoder(spdif_ctx->codec_id);
+    const AVCodec *codec = avcodec_find_decoder(spdif_ctx->codec_id);
     if (!codec)
         goto done;
 

audio/filter/af_lavcac3enc.c

@@ -68,7 +68,7 @@ struct priv {
     struct mp_aframe *in_frame;
     struct mp_aframe_pool *out_pool;
 
-    struct AVCodec        *lavc_acodec;
+    const struct AVCodec  *lavc_acodec;
     struct AVCodecContext *lavc_actx;
     int bit_rate;
     int out_samples;    // upper bound on encoded output per AC3 frame

common/av_common.c

@@ -270,7 +270,7 @@ int mp_codec_to_av_codec_id(const char *codec)
         if (desc)
             id = desc->id;
         if (id == AV_CODEC_ID_NONE) {
-            AVCodec *avcodec = avcodec_find_decoder_by_name(codec);
+            const AVCodec *avcodec = avcodec_find_decoder_by_name(codec);
             if (avcodec)
                 id = avcodec->id;
         }
@@ -285,7 +285,7 @@ const char *mp_codec_from_av_codec_id(int codec_id)
     if (desc)
         name = desc->name;
     if (!name) {
-        AVCodec *avcodec = avcodec_find_decoder(codec_id);
+        const AVCodec *avcodec = avcodec_find_decoder(codec_id);
         if (avcodec)
             name = avcodec->name;
     }

common/encode_lavc.c

@@ -735,7 +735,7 @@ static void encoder_destroy(void *ptr)
     free_stream(p->twopass_bytebuffer);
 }
 
-static AVCodec *find_codec_for(struct encode_lavc_context *ctx,
+static const AVCodec *find_codec_for(struct encode_lavc_context *ctx,
                                enum stream_type type, bool *used_auto)
 {
     char *codec_name = type == STREAM_VIDEO
@@ -746,7 +746,7 @@ static AVCodec *find_codec_for(struct encode_lavc_context *ctx,
 
     *used_auto = !(codec_name && codec_name[0]);
 
-    AVCodec *codec;
+    const AVCodec *codec;
     if (*used_auto) {
         codec = avcodec_find_encoder(av_guess_codec(ctx->oformat, NULL,
                                      ctx->options->file, NULL,
@@ -797,7 +797,7 @@ struct encoder_context *encoder_context_alloc(struct encode_lavc_context *ctx,
     };
 
     bool auto_codec;
-    AVCodec *codec = find_codec_for(ctx, type, &auto_codec);
+    const AVCodec *codec = find_codec_for(ctx, type, &auto_codec);
     const char *tname = stream_type_name(type);
 
     if (!codec) {

common/encode_lavc.h

@@ -41,7 +41,7 @@ struct encode_lavc_context {
     struct encode_opts *options;
     struct mp_log *log;
     struct encode_priv *priv;
-    AVOutputFormat *oformat;
+    const AVOutputFormat *oformat;
     const char *filename;
 
     // All entry points must be guarded with the lock. Functions called by
@@ -71,7 +71,7 @@ struct encoder_context {
     struct mpv_global *global;
     struct encode_opts *options;
     struct mp_log *log;
-    AVOutputFormat *oformat;
+    const AVOutputFormat *oformat;
 
     // (avoid using this)
     struct encode_lavc_context *encode_lavc_ctx;

demux/demux_lavf.c

@@ -227,7 +227,7 @@ typedef struct lavf_priv {
     bool own_stream;
     char *filename;
     struct format_hack format_hack;
-    AVInputFormat *avif;
+    const AVInputFormat *avif;
     int avif_flags;
     AVFormatContext *avfc;
     AVIOContext *pb;
@@ -443,7 +443,7 @@ static int lavf_check_file(demuxer_t *demuxer, enum demux_check check)
     if (!lavfdopts->allow_mimetype || !mime_type)
         mime_type = "";
 
-    AVInputFormat *forced_format = NULL;
+    const AVInputFormat *forced_format = NULL;
     const char *format = lavfdopts->format;
     if (!format)
         format = s->lavf_type;

sub/lavc_conv.c

@@ -75,7 +75,7 @@ struct lavc_conv *lavc_conv_create(struct mp_log *log, const char *codec_name,
     AVCodecContext *avctx = NULL;
     AVDictionary *opts = NULL;
     const char *fmt = get_lavc_format(priv->codec);
-    AVCodec *codec = avcodec_find_decoder(mp_codec_to_av_codec_id(fmt));
+    const AVCodec *codec = avcodec_find_decoder(mp_codec_to_av_codec_id(fmt));
     if (!codec)
         goto error;
     avctx = avcodec_alloc_context3(codec);

sub/sd_lavc.c

@@ -91,7 +91,7 @@ static int init(struct sd *sd)
 
     struct sd_lavc_priv *priv = talloc_zero(NULL, struct sd_lavc_priv);
     AVCodecContext *ctx = NULL;
-    AVCodec *sub_codec = avcodec_find_decoder(cid);
+    const AVCodec *sub_codec = avcodec_find_decoder(cid);
     if (!sub_codec)
         goto error;
     ctx = avcodec_alloc_context3(sub_codec);

video/image_writer.c

@@ -103,7 +103,7 @@ static bool write_lavc(struct image_writer_ctx *ctx, mp_image_t *image, FILE *fp
 
     av_init_packet(&pkt);
 
-    struct AVCodec *codec;
+    const AVCodec *codec;
     if (ctx->opts->format == AV_CODEC_ID_WEBP) {
         codec = avcodec_find_encoder_by_name("libwebp"); // non-animated encoder
     } else {
@@ -251,7 +251,7 @@ static bool write_jpeg(struct image_writer_ctx *ctx, mp_image_t *image, FILE *fp
 
 #endif
 
-static int get_encoder_format(struct AVCodec *codec, int srcfmt, bool highdepth)
+static int get_encoder_format(const AVCodec *codec, int srcfmt, bool highdepth)
 {
     const enum AVPixelFormat *pix_fmts = codec->pix_fmts;
     int current = 0;
@@ -277,7 +277,7 @@ static int get_encoder_format(struct AVCodec *codec, int srcfmt, bool highdepth)
 
 static int get_target_format(struct image_writer_ctx *ctx)
 {
-    struct AVCodec *codec = avcodec_find_encoder(ctx->opts->format);
+    const AVCodec *codec = avcodec_find_encoder(ctx->opts->format);
     if (!codec)
         goto unknown;