const AVCodecParameters *audio_codecpar = format_ctx->streams[audio_stream_index]->codecpar;
audio_timebase = format_ctx->streams[audio_stream_index]->time_base;
if (avcodec_parameters_to_context(audio_codec_ctx.get(), audio_codecpar) < 0) {
const AVCodecParameters *audio_codecpar = format_ctx->streams[audio_stream_index]->codecpar;
audio_timebase = format_ctx->streams[audio_stream_index]->time_base;
if (avcodec_parameters_to_context(audio_codec_ctx.get(), audio_codecpar) < 0) {