spdif-loop/NOTES at master · corecode/spdif-loop · GitHub

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libavformat sequence

init

av_register_all();
avcodec_register_all();

sndinfmt = av_find_input_format("alsa");
avformat_open_input(&sndinctx, "hw:1", sndinfmt, NULL);

mock up another input for spdif demux:

spdifctx = avformat_alloc_context();
spdifctx->pb = avio_alloc_context(buf, bufsize, 0, mydata, read_cb, NULL, NULL);
spdiffmt = av_find_input_format("spdif");
avformat_open_input(&spdifctx, NULL, spidffmt, NULL);

get decoder

codec = avcodec_find_decoder(spdifcodec_id);
codecctx = avcodec_alloc_context3(codec);
avcodec_open2(&codecctx, codec, NULL);

outframe = avcodec_alloc_frame();
processed_len = avcodec_decode_audio4(codecctx, outframe, &got_frame, inpkt);

/* advance inpkt by processed_len */

codecctx->sample_rate;
codecctx->channels;
codecctx->sample_fmt;
codecctx->channel_layout;

outframe->data
outframe->nb_samples
outlen = av_samples_get_buffer_size(NULL, codecctx->channels, outframe->nb_samples, codecctx->sample_fmt, 1);

play with libao

ao_initialize();
ao_sample_format outfmt;
memset(&outfmt, 0, sizeof(outfmt));
outfmt.bits = ...;
outfmt.channels = ...;
outfmt.rate = ...;
outfmt.byte_format = ...;

outdev = ao_open_live(ao_default_driver_id(), &outfmt, NULL);

ao_play(outdev, buf, bufsize);