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115 lines
3.9 KiB
C++
115 lines
3.9 KiB
C++
/***
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This file is part of snapcast
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Copyright (C) 2015 Hannes Ellinger
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "opus_decoder.hpp"
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#include "common/aixlog.hpp"
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#include "common/snap_exception.hpp"
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#include "common/str_compat.hpp"
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namespace decoder
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{
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#define ID_OPUS 0x4F505553
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/// int: Number of samples per channel in the input signal.
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/// This must be an Opus frame size for the encoder's sampling rate. For example, at 48 kHz the
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/// permitted values are 120, 240, 480, 960, 1920, and 2880.
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/// Passing in a duration of less than 10 ms (480 samples at 48 kHz) will prevent the encoder from using the LPC or hybrid modes.
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static constexpr int const_max_frame_size = 2880;
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OpusDecoder::OpusDecoder() : Decoder(), dec_(nullptr)
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{
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pcm_.resize(120);
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}
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OpusDecoder::~OpusDecoder()
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{
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if (dec_ != nullptr)
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opus_decoder_destroy(dec_);
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}
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bool OpusDecoder::decode(msg::PcmChunk* chunk)
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{
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int frame_size = 0;
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while ((frame_size = opus_decode(dec_, (unsigned char*)chunk->payload, chunk->payloadSize, pcm_.data(), pcm_.size() / sample_format_.channels, 0)) ==
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OPUS_BUFFER_TOO_SMALL)
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{
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if (pcm_.size() < const_max_frame_size * sample_format_.channels)
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{
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pcm_.resize(pcm_.size() * 2);
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LOG(INFO) << "OPUS encoding buffer too small, resizing to " << pcm_.size() / sample_format_.channels << " samples per channel\n";
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}
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else
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break;
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}
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if (frame_size < 0)
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{
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LOG(ERROR) << "Failed to decode chunk: " << opus_strerror(frame_size) << ", IN size: " << chunk->payloadSize << ", OUT size: " << pcm_.size() << '\n';
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return false;
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}
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else
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{
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LOG(DEBUG) << "Decoded chunk: size " << chunk->payloadSize << " bytes, decoded " << frame_size << " samples" << '\n';
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// copy encoded data to chunk
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chunk->payloadSize = frame_size * sample_format_.channels * sizeof(opus_int16);
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chunk->payload = (char*)realloc(chunk->payload, chunk->payloadSize);
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memcpy(chunk->payload, (char*)pcm_.data(), chunk->payloadSize);
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return true;
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}
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}
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SampleFormat OpusDecoder::setHeader(msg::CodecHeader* chunk)
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{
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// decode the opus pseudo header
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if (chunk->payloadSize < 12)
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throw SnapException("OPUS header too small");
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// decode the "opus id" magic number, this is our constant part that must match
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uint32_t id_opus;
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memcpy(&id_opus, chunk->payload, sizeof(id_opus));
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if (SWAP_32(id_opus) != ID_OPUS)
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throw SnapException("Not an Opus pseudo header");
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// decode the sampleformat
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uint32_t rate;
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memcpy(&rate, chunk->payload + 4, sizeof(id_opus));
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uint16_t bits;
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memcpy(&bits, chunk->payload + 8, sizeof(bits));
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uint16_t channels;
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memcpy(&channels, chunk->payload + 10, sizeof(channels));
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sample_format_.setFormat(SWAP_32(rate), SWAP_16(bits), SWAP_16(channels));
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LOG(DEBUG) << "Opus sampleformat: " << sample_format_.getFormat() << "\n";
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// create the decoder
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int error;
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dec_ = opus_decoder_create(sample_format_.rate, sample_format_.channels, &error);
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if (error != 0)
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throw SnapException("Failed to initialize Opus decoder: " + std::string(opus_strerror(error)));
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return sample_format_;
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}
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} // namespace decoder
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