get pixel formats and sample formats

c_src/xav/xav_decoder.c

@@ -267,6 +267,41 @@ ERL_NIF_TERM flush(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
   return xav_nif_ok(env, enif_make_list_from_array(env, frame_terms, frames_count));
 }
 
+ERL_NIF_TERM pixel_formats(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+  ERL_NIF_TERM result = enif_make_list(env, 0);
+
+  const AVPixFmtDescriptor *desc = NULL;
+
+  while ((desc = av_pix_fmt_desc_next(desc))) {
+    ERL_NIF_TERM name = enif_make_atom(env, desc->name);
+    ERL_NIF_TERM nb_components = enif_make_int(env, desc->nb_components);
+    ERL_NIF_TERM is_hwaccel =
+        enif_make_atom(env, desc->flags & AV_PIX_FMT_FLAG_HWACCEL ? "true" : "false");
+
+    result =
+        enif_make_list_cell(env, enif_make_tuple3(env, name, nb_components, is_hwaccel), result);
+  }
+
+  return result;
+}
+
+ERL_NIF_TERM sample_formats(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
+  ERL_NIF_TERM result = enif_make_list(env, 0);
+
+  for (int fmt = 0; fmt < AV_SAMPLE_FMT_NB; fmt++) {
+    enum AVSampleFormat sample_format = (enum AVSampleFormat)fmt;
+    const char *name = av_get_sample_fmt_name(sample_format);
+    int nb_bytes = av_get_bytes_per_sample(sample_format);
+
+    ERL_NIF_TERM desc =
+        enif_make_tuple2(env, enif_make_atom(env, name), enif_make_int(env, nb_bytes));
+
+    result = enif_make_list_cell(env, desc, result);
+  }
+
+  return result;
+}
+
 static int init_audio_converter(struct XavDecoder *xav_decoder) {
   xav_decoder->ac = audio_converter_alloc();
 
@@ -345,7 +380,9 @@ void free_xav_decoder(ErlNifEnv *env, void *obj) {
 
 static ErlNifFunc xav_funcs[] = {{"new", 6, new},
                                  {"decode", 4, decode, ERL_NIF_DIRTY_JOB_CPU_BOUND},
-                                 {"flush", 1, flush, ERL_NIF_DIRTY_JOB_CPU_BOUND}};
+                                 {"flush", 1, flush, ERL_NIF_DIRTY_JOB_CPU_BOUND},
+                                 {"pixel_formats", 0, pixel_formats},
+                                 {"sample_formats", 0, sample_formats}};
 
 static int load(ErlNifEnv *env, void **priv, ERL_NIF_TERM load_info) {
   xav_decoder_resource_type =

lib/xav.ex

@@ -0,0 +1,24 @@
+defmodule Xav do
+  @moduledoc File.read!("README.md")
+
+  @doc """
+  Get all available pixel formats.
+
+  The result is a list of 3-element tuples `{name, nb_components, hw_accelerated_format?}`:
+    * `name` - The name of the pixel format.
+    * `nb_components` - The number of the components in the pixel format.
+    * `hw_accelerated_format?` - Whether the pixel format is a hardware accelerated format.
+  """
+  @spec pixel_formats() :: [{atom(), integer(), boolean()}]
+  def pixel_formats(), do: Xav.Decoder.NIF.pixel_formats() |> Enum.reverse()
+
+  @doc """
+  Get all available audio sample formats.
+
+  The result is a list of 2-element tuples `{name, nb_bytes}`:
+    * `name` - The name of the sample format.
+    * `nb_bytes` - The number of bytes per sample.
+  """
+  @spec sample_formats() :: [{atom(), integer()}]
+  def sample_formats(), do: Xav.Decoder.NIF.sample_formats() |> Enum.reverse()
+end

lib/decoder_nif.ex → lib/xav/decoder_nif.ex

@@ -15,4 +15,8 @@ defmodule Xav.Decoder.NIF do
   def decode(_decoder, _data, _pts, _dts), do: :erlang.nif_error(:undef)
 
   def flush(_decoder), do: :erlang.nif_error(:undef)
+
+  def pixel_formats(), do: :erlang.nif_error(:undef)
+
+  def sample_formats(), do: :erlang.nif_error(:undef)
 end