avcodec/codec, allcodecs: Constify the AVCodec API

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

doc/APIchanges

@@ -14,6 +14,11 @@ libavutil:     2017-10-21
 
 API changes, most recent first:
 
+2021-04-27 - xxxxxxxxxx - lavc yyyyyyyyy - codec.h
+  avcodec_find_encoder_by_name(), avcodec_find_encoder(),
+  avcodec_find_decoder_by_name() and avcodec_find_decoder()
+  now return a pointer to const AVCodec.
+
 2021-04-27 - xxxxxxxxxx - lavf yyyyyyyyy - avformat.h
   Constified AVFormatContext.*_codec.
 

doc/examples/demuxing_decoding.c

@@ -149,7 +149,7 @@ static int open_codec_context(int *stream_idx,
 {
     int ret, stream_index;
     AVStream *st;
-    AVCodec *dec = NULL;
+    const AVCodec *dec = NULL;
     AVDictionary *opts = NULL;
 
     ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);

doc/examples/muxing.c

@@ -121,7 +121,7 @@ static int write_frame(AVFormatContext *fmt_ctx, AVCodecContext *c,
 
 /* Add an output stream. */
 static void add_stream(OutputStream *ost, AVFormatContext *oc,
-                       AVCodec **codec,
+                       const AVCodec **codec,
                        enum AVCodecID codec_id)
 {
     AVCodecContext *c;
@@ -242,7 +242,8 @@ static AVFrame *alloc_audio_frame(enum AVSampleFormat sample_fmt,
     return frame;
 }
 
-static void open_audio(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
+static void open_audio(AVFormatContext *oc, const AVCodec *codec,
+                       OutputStream *ost, AVDictionary *opt_arg)
 {
     AVCodecContext *c;
     int nb_samples;
@@ -405,7 +406,8 @@ static AVFrame *alloc_picture(enum AVPixelFormat pix_fmt, int width, int height)
     return picture;
 }
 
-static void open_video(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
+static void open_video(AVFormatContext *oc, const AVCodec *codec,
+                       OutputStream *ost, AVDictionary *opt_arg)
 {
     int ret;
     AVCodecContext *c = ost->enc;
@@ -539,7 +541,7 @@ int main(int argc, char **argv)
     const AVOutputFormat *fmt;
     const char *filename;
     AVFormatContext *oc;
-    AVCodec *audio_codec, *video_codec;
+    const AVCodec *audio_codec, *video_codec;
     int ret;
     int have_video = 0, have_audio = 0;
     int encode_video = 0, encode_audio = 0;

doc/examples/transcode_aac.c

@@ -60,7 +60,7 @@ static int open_input_file(const char *filename,
                            AVCodecContext **input_codec_context)
 {
     AVCodecContext *avctx;
-    AVCodec *input_codec;
+    const AVCodec *input_codec;
     int error;
 
     /* Open the input file to read from it. */
@@ -144,7 +144,7 @@ static int open_output_file(const char *filename,
     AVCodecContext *avctx          = NULL;
     AVIOContext *output_io_context = NULL;
     AVStream *stream               = NULL;
-    AVCodec *output_codec          = NULL;
+    const AVCodec *output_codec    = NULL;
     int error;
 
     /* Open the output file to write to it. */

doc/examples/transcoding.c

@@ -77,7 +77,7 @@ static int open_input_file(const char *filename)
 
     for (i = 0; i < ifmt_ctx->nb_streams; i++) {
         AVStream *stream = ifmt_ctx->streams[i];
-        AVCodec *dec = avcodec_find_decoder(stream->codecpar->codec_id);
+        const AVCodec *dec = avcodec_find_decoder(stream->codecpar->codec_id);
         AVCodecContext *codec_ctx;
         if (!dec) {
             av_log(NULL, AV_LOG_ERROR, "Failed to find decoder for stream #%u\n", i);
@@ -122,7 +122,7 @@ static int open_output_file(const char *filename)
     AVStream *out_stream;
     AVStream *in_stream;
     AVCodecContext *dec_ctx, *enc_ctx;
-    AVCodec *encoder;
+    const AVCodec *encoder;
     int ret;
     unsigned int i;
 

doc/examples/vaapi_encode.c

@@ -105,7 +105,7 @@ int main(int argc, char *argv[])
     FILE *fin = NULL, *fout = NULL;
     AVFrame *sw_frame = NULL, *hw_frame = NULL;
     AVCodecContext *avctx = NULL;
-    AVCodec *codec = NULL;
+    const AVCodec *codec = NULL;
     const char *enc_name = "h264_vaapi";
 
     if (argc < 5) {

doc/examples/vaapi_transcode.c

@@ -142,7 +142,7 @@ end:
     return ret;
 }
 
-static int dec_enc(AVPacket *pkt, AVCodec *enc_codec)
+static int dec_enc(AVPacket *pkt, const AVCodec *enc_codec)
 {
     AVFrame *frame;
     int ret = 0;
@@ -226,9 +226,9 @@ fail:
 
 int main(int argc, char **argv)
 {
+    const AVCodec *enc_codec;
     int ret = 0;
     AVPacket *dec_pkt;
-    AVCodec *enc_codec;
 
     if (argc != 4) {
         fprintf(stderr, "Usage: %s <input file> <encode codec> <output file>\n"

libavcodec/allcodecs.c

@@ -873,7 +873,7 @@ static enum AVCodecID remap_deprecated_codec_id(enum AVCodecID id)
     }
 }
 
-static AVCodec *find_codec(enum AVCodecID id, int (*x)(const AVCodec *))
+static const AVCodec *find_codec(enum AVCodecID id, int (*x)(const AVCodec *))
 {
     const AVCodec *p, *experimental = NULL;
     void *i = 0;
@@ -887,24 +887,24 @@ static AVCodec *find_codec(enum AVCodecID id, int (*x)(const AVCodec *))
             if (p->capabilities & AV_CODEC_CAP_EXPERIMENTAL && !experimental) {
                 experimental = p;
             } else
-                return (AVCodec*)p;
+                return p;
         }
     }
 
-    return (AVCodec*)experimental;
+    return experimental;
 }
 
-AVCodec *avcodec_find_encoder(enum AVCodecID id)
+const AVCodec *avcodec_find_encoder(enum AVCodecID id)
 {
     return find_codec(id, av_codec_is_encoder);
 }
 
-AVCodec *avcodec_find_decoder(enum AVCodecID id)
+const AVCodec *avcodec_find_decoder(enum AVCodecID id)
 {
     return find_codec(id, av_codec_is_decoder);
 }
 
-static AVCodec *find_codec_by_name(const char *name, int (*x)(const AVCodec *))
+static const AVCodec *find_codec_by_name(const char *name, int (*x)(const AVCodec *))
 {
     void *i = 0;
     const AVCodec *p;
@@ -916,18 +916,18 @@ static AVCodec *find_codec_by_name(const char *name, int (*x)(const AVCodec *))
         if (!x(p))
             continue;
         if (strcmp(name, p->name) == 0)
-            return (AVCodec*)p;
+            return p;
     }
 
     return NULL;
 }
 
-AVCodec *avcodec_find_encoder_by_name(const char *name)
+const AVCodec *avcodec_find_encoder_by_name(const char *name)
 {
     return find_codec_by_name(name, av_codec_is_encoder);
 }
 
-AVCodec *avcodec_find_decoder_by_name(const char *name)
+const AVCodec *avcodec_find_decoder_by_name(const char *name)
 {
     return find_codec_by_name(name, av_codec_is_decoder);
 }

libavcodec/codec.h

@@ -367,7 +367,7 @@ const AVCodec *av_codec_iterate(void **opaque);
  * @param id AVCodecID of the requested decoder
  * @return A decoder if one was found, NULL otherwise.
  */
-AVCodec *avcodec_find_decoder(enum AVCodecID id);
+const AVCodec *avcodec_find_decoder(enum AVCodecID id);
 
 /**
  * Find a registered decoder with the specified name.
@@ -375,7 +375,7 @@ AVCodec *avcodec_find_decoder(enum AVCodecID id);
  * @param name name of the requested decoder
  * @return A decoder if one was found, NULL otherwise.
  */
-AVCodec *avcodec_find_decoder_by_name(const char *name);
+const AVCodec *avcodec_find_decoder_by_name(const char *name);
 
 /**
  * Find a registered encoder with a matching codec ID.
@@ -383,7 +383,7 @@ AVCodec *avcodec_find_decoder_by_name(const char *name);
  * @param id AVCodecID of the requested encoder
  * @return An encoder if one was found, NULL otherwise.
  */
-AVCodec *avcodec_find_encoder(enum AVCodecID id);
+const AVCodec *avcodec_find_encoder(enum AVCodecID id);
 
 /**
  * Find a registered encoder with the specified name.
@@ -391,7 +391,7 @@ AVCodec *avcodec_find_encoder(enum AVCodecID id);
  * @param name name of the requested encoder
  * @return An encoder if one was found, NULL otherwise.
  */
-AVCodec *avcodec_find_encoder_by_name(const char *name);
+const AVCodec *avcodec_find_encoder_by_name(const char *name);
 /**
  * @return a non-zero number if codec is an encoder, zero otherwise
  */

libavdevice/dshow.c

@@ -369,7 +369,7 @@ dshow_cycle_formats(AVFormatContext *avctx, enum dshowDeviceType devtype,
                 enum AVPixelFormat pix_fmt = dshow_pixfmt(bih->biCompression, bih->biBitCount);
                 if (pix_fmt == AV_PIX_FMT_NONE) {
                     enum AVCodecID codec_id = av_codec_get_id(tags, bih->biCompression);
-                    AVCodec *codec = avcodec_find_decoder(codec_id);
+                    const AVCodec *codec = avcodec_find_decoder(codec_id);
                     if (codec_id == AV_CODEC_ID_NONE || !codec) {
                         av_log(avctx, AV_LOG_INFO, "  unknown compression type 0x%X", (int) bih->biCompression);
                     } else {

tests/api/api-band-test.c

@@ -66,7 +66,7 @@ static void draw_horiz_band(AVCodecContext *ctx, const AVFrame *fr, int offset[4
 
 static int video_decode(const char *input_filename)
 {
-    AVCodec *codec = NULL;
+    const AVCodec *codec = NULL;
     AVCodecContext *ctx= NULL;
     AVCodecParameters *origin_par = NULL;
     uint8_t *byte_buffer = NULL;

tests/api/api-flac-test.c

@@ -48,7 +48,7 @@ static int generate_raw_frame(uint16_t *frame_data, int i, int sample_rate,
     return 0;
 }
 
-static int init_encoder(AVCodec *enc, AVCodecContext **enc_ctx,
+static int init_encoder(const AVCodec *enc, AVCodecContext **enc_ctx,
                         int64_t ch_layout, int sample_rate)
 {
     AVCodecContext *ctx;
@@ -78,7 +78,7 @@ static int init_encoder(AVCodec *enc, AVCodecContext **enc_ctx,
     return 0;
 }
 
-static int init_decoder(AVCodec *dec, AVCodecContext **dec_ctx,
+static int init_decoder(const AVCodec *dec, AVCodecContext **dec_ctx,
                         int64_t ch_layout)
 {
     AVCodecContext *ctx;
@@ -105,8 +105,8 @@ static int init_decoder(AVCodec *dec, AVCodecContext **dec_ctx,
     return 0;
 }
 
-static int run_test(AVCodec *enc, AVCodec *dec, AVCodecContext *enc_ctx,
-                    AVCodecContext *dec_ctx)
+static int run_test(const AVCodec *enc, const AVCodec *dec,
+                    AVCodecContext *enc_ctx, AVCodecContext *dec_ctx)
 {
     AVPacket *enc_pkt;
     AVFrame *in_frame, *out_frame;
@@ -244,7 +244,7 @@ static int run_test(AVCodec *enc, AVCodec *dec, AVCodecContext *enc_ctx,
 
 int main(void)
 {
-    AVCodec *enc = NULL, *dec = NULL;
+    const AVCodec *enc = NULL, *dec = NULL;
     AVCodecContext *enc_ctx = NULL, *dec_ctx = NULL;
     uint64_t channel_layouts[] = {AV_CH_LAYOUT_STEREO, AV_CH_LAYOUT_5POINT1_BACK, AV_CH_LAYOUT_SURROUND, AV_CH_LAYOUT_STEREO_DOWNMIX};
     int sample_rates[] = {8000, 44100, 48000, 192000};

tests/api/api-h264-test.c

@@ -32,7 +32,7 @@
 
 static int video_decode_example(const char *input_filename)
 {
-    AVCodec *codec = NULL;
+    const AVCodec *codec = NULL;
     AVCodecContext *ctx= NULL;
     AVCodecParameters *origin_par = NULL;
     AVFrame *fr = NULL;

tests/api/api-seek-test.c

@@ -184,7 +184,7 @@ static long int read_seek_range(const char *string_with_number)
 
 static int seek_test(const char *input_filename, const char *start, const char *end)
 {
-    AVCodec *codec = NULL;
+    const AVCodec *codec = NULL;
     AVCodecContext *ctx= NULL;
     AVCodecParameters *origin_par = NULL;
     AVPacket *pkt = NULL;

tools/target_dec_fuzzer.c

@@ -59,7 +59,7 @@
 
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
 
-extern AVCodec * codec_list[];
+extern const AVCodec * codec_list[];
 
 static void error(const char *err)
 {
@@ -67,10 +67,10 @@ static void error(const char *err)
     exit(1);
 }
 
-static AVCodec *c = NULL;
-static AVCodec *AVCodecInitialize(enum AVCodecID codec_id)
+static const AVCodec *c = NULL;
+static const AVCodec *AVCodecInitialize(enum AVCodecID codec_id)
 {
-    AVCodec *res;
+    const AVCodec *res;
 
     res = avcodec_find_decoder(codec_id);
     if (!res)