일단 ffmpeg파일 인코딩/디코딩 예제 코드 완성

tests/ffmpeg_decode_audio.cc

@@ -0,0 +1,155 @@
+#include <fstream>
+
+#include "ffmpeg/libavcodec.h"
+#include "precomp.h"
+
+int main() {
+  const char* input_filename = "golden.webm";
+  const char* output_filename = "output.pcm";
+
+  AVFormatContext* fmt_ctx = NULL;
+  AVCodecContext* codec_ctx = NULL;
+  const AVCodec* codec = NULL;
+  AVPacket* packet = NULL;
+  AVFrame* frame = NULL;
+  SwrContext* swr_ctx = NULL;
+  FILE* outfile = NULL;
+
+  if (avformat_open_input(&fmt_ctx, input_filename, NULL, NULL) < 0) {
+    fprintf(stderr, "Could not open input file\n");
+    return -1;
+  }
+
+  if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
+    fprintf(stderr, "Could not find stream info\n");
+    return -1;
+  }
+
+  int stream_index = -1;
+  for (unsigned i = 0; i < fmt_ctx->nb_streams; i++) {
+    if (fmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
+      stream_index = i;
+      break;
+    }
+  }
+  if (stream_index == -1) {
+    fprintf(stderr, "Could not find audio stream\n");
+    return -1;
+  }
+
+  codec =
+      avcodec_find_decoder(fmt_ctx->streams[stream_index]->codecpar->codec_id);
+  if (!codec) {
+    fprintf(stderr, "Could not find decoder\n");
+    return -1;
+  }
+
+  codec_ctx = avcodec_alloc_context3(codec);
+  if (!codec_ctx) {
+    fprintf(stderr, "Could not allocate codec context\n");
+    return -1;
+  }
+
+  if (avcodec_parameters_to_context(
+          codec_ctx, fmt_ctx->streams[stream_index]->codecpar) < 0) {
+    fprintf(stderr, "Failed to copy codec parameters\n");
+    return -1;
+  }
+
+  if (avcodec_open2(codec_ctx, codec, NULL) < 0) {
+    fprintf(stderr, "Could not open codec\n");
+    return -1;
+  }
+
+  packet = av_packet_alloc();
+  frame = av_frame_alloc();
+  if (!packet || !frame) {
+    fprintf(stderr, "Could not allocate packet or frame\n");
+    return -1;
+  }
+
+  outfile = fopen(output_filename, "wb");
+  if (!outfile) {
+    fprintf(stderr, "Could not open output file\n");
+    return -1;
+  }
+
+  // AVChannelLayout 초기화
+  AVChannelLayout in_layout, out_layout;
+  if (av_channel_layout_copy(&in_layout, &codec_ctx->ch_layout) < 0) {
+    fprintf(stderr, "Failed to copy channel layout\n");
+    return -1;
+  }
+  av_channel_layout_default(&out_layout, 2);  // 스테레오
+
+  swr_ctx = NULL;  // 먼저 NULL로 선언
+  if (swr_alloc_set_opts2(&swr_ctx, &out_layout, AV_SAMPLE_FMT_S16, 48000,
+                          &in_layout, codec_ctx->sample_fmt,
+                          codec_ctx->sample_rate, 0, NULL) < 0) {
+    fprintf(stderr, "Failed to allocate and set SwrContext\n");
+    return -1;
+  }
+
+  if (swr_init(swr_ctx) < 0) {
+    fprintf(stderr, "Failed to initialize SwrContext\n");
+    return -1;
+  }
+
+  while (av_read_frame(fmt_ctx, packet) >= 0) {
+    if (packet->stream_index == stream_index) {
+      if (avcodec_send_packet(codec_ctx, packet) == 0) {
+        while (avcodec_receive_frame(codec_ctx, frame) == 0) {
+          int out_samples =
+              av_rescale_rnd(swr_get_delay(swr_ctx, codec_ctx->sample_rate) +
+                                 frame->nb_samples,
+                             48000, codec_ctx->sample_rate, AV_ROUND_UP);
+
+          uint8_t** out_buf = NULL;
+          int out_linesize = 0;
+          av_samples_alloc_array_and_samples(&out_buf, &out_linesize, 2,
+                                             out_samples, AV_SAMPLE_FMT_S16, 0);
+
+          int converted_samples =
+              swr_convert(swr_ctx, out_buf, out_samples,
+                          (const uint8_t**)frame->data, frame->nb_samples);
+
+          fwrite(out_buf[0], 1, converted_samples * 2 * 2, outfile);
+          av_freep(&out_buf[0]);
+          free(out_buf);
+        }
+      }
+    }
+    av_packet_unref(packet);
+  }
+
+  // 디코더 플러시
+  avcodec_send_packet(codec_ctx, NULL);
+  while (avcodec_receive_frame(codec_ctx, frame) == 0) {
+    int out_samples = av_rescale_rnd(
+        swr_get_delay(swr_ctx, codec_ctx->sample_rate) + frame->nb_samples,
+        48000, codec_ctx->sample_rate, AV_ROUND_UP);
+
+    uint8_t** out_buf = NULL;
+    int out_linesize = 0;
+    av_samples_alloc_array_and_samples(&out_buf, &out_linesize, 2, out_samples,
+                                       AV_SAMPLE_FMT_S16, 0);
+
+    int converted_samples =
+        swr_convert(swr_ctx, out_buf, out_samples, (const uint8_t**)frame->data,
+                    frame->nb_samples);
+
+    fwrite(out_buf[0], 1, converted_samples * 2 * 2, outfile);
+    av_freep(&out_buf[0]);
+    free(out_buf);
+  }
+
+  fclose(outfile);
+  swr_free(&swr_ctx);
+  av_frame_free(&frame);
+  av_packet_free(&packet);
+  avcodec_free_context(&codec_ctx);
+  avformat_close_input(&fmt_ctx);
+
+  printf("Decoding finished, output saved to %s\n", output_filename);
+  return 0;
+}