AJM: Added some missing features (#1489)

* AJM: Added support for different PCM formats

* updated libatrac9 ref

* remove log

* Add support for non-interleaved flag

* Added support for output sideband format query

externals/LibAtrac9

@@ -1 +1 @@
-Subproject commit 82767fe38823c32536726ea798f392b0b49e66b9
+Subproject commit 3acdcdc78f129c2e6145331ff650fa76dd88d62c

src/core/libraries/ajm/ajm.cpp

@@ -13,8 +13,31 @@
 
 namespace Libraries::Ajm {
 
+constexpr int ORBIS_AJM_CHANNELMASK_MONO = 0x0004;
+constexpr int ORBIS_AJM_CHANNELMASK_STEREO = 0x0003;
+constexpr int ORBIS_AJM_CHANNELMASK_QUAD = 0x0033;
+constexpr int ORBIS_AJM_CHANNELMASK_5POINT1 = 0x060F;
+constexpr int ORBIS_AJM_CHANNELMASK_7POINT1 = 0x063F;
+
 static std::unique_ptr<AjmContext> context{};
 
+u32 GetChannelMask(u32 num_channels) {
+    switch (num_channels) {
+    case 1:
+        return ORBIS_AJM_CHANNELMASK_MONO;
+    case 2:
+        return ORBIS_AJM_CHANNELMASK_STEREO;
+    case 4:
+        return ORBIS_AJM_CHANNELMASK_QUAD;
+    case 6:
+        return ORBIS_AJM_CHANNELMASK_5POINT1;
+    case 8:
+        return ORBIS_AJM_CHANNELMASK_7POINT1;
+    default:
+        UNREACHABLE();
+    }
+}
+
 int PS4_SYSV_ABI sceAjmBatchCancel(const u32 context_id, const u32 batch_id) {
     LOG_INFO(Lib_Ajm, "called context_id = {} batch_id = {}", context_id, batch_id);
     return context->BatchCancel(batch_id);

src/core/libraries/ajm/ajm.h

@@ -137,9 +137,12 @@ union AjmInstanceFlags {
         u64 codec : 28;
     };
 };
+static_assert(sizeof(AjmInstanceFlags) == 8);
 
 struct AjmDecMp3ParseFrame;
 
+u32 GetChannelMask(u32 num_channels);
+
 int PS4_SYSV_ABI sceAjmBatchCancel(const u32 context_id, const u32 batch_id);
 int PS4_SYSV_ABI sceAjmBatchErrorDump();
 void* PS4_SYSV_ABI sceAjmBatchJobControlBufferRa(void* p_buffer, u32 instance_id, u64 flags,

src/core/libraries/ajm/ajm_at9.cpp

@@ -14,8 +14,8 @@ extern "C" {
 
 namespace Libraries::Ajm {
 
-AjmAt9Decoder::AjmAt9Decoder() {
-    m_handle = Atrac9GetHandle();
+AjmAt9Decoder::AjmAt9Decoder(AjmFormatEncoding format, AjmAt9CodecFlags flags)
+    : m_format(format), m_flags(flags), m_handle(Atrac9GetHandle()) {
     ASSERT_MSG(m_handle, "Atrac9GetHandle failed");
     AjmAt9Decoder::Reset();
 }
@@ -40,7 +40,20 @@ void AjmAt9Decoder::Initialize(const void* buffer, u32 buffer_size) {
     const auto params = reinterpret_cast<const AjmDecAt9InitializeParameters*>(buffer);
     std::memcpy(m_config_data, params->config_data, ORBIS_AT9_CONFIG_DATA_SIZE);
     AjmAt9Decoder::Reset();
-    m_pcm_buffer.resize(m_codec_info.frameSamples * m_codec_info.channels, 0);
+    m_pcm_buffer.resize(m_codec_info.frameSamples * m_codec_info.channels * GetPointCodeSize(), 0);
+}
+
+u8 AjmAt9Decoder::GetPointCodeSize() {
+    switch (m_format) {
+    case AjmFormatEncoding::S16:
+        return sizeof(s16);
+    case AjmFormatEncoding::S32:
+        return sizeof(s32);
+    case AjmFormatEncoding::Float:
+        return sizeof(float);
+    default:
+        UNREACHABLE();
+    }
 }
 
 void AjmAt9Decoder::GetInfo(void* out_info) {
@@ -53,28 +66,56 @@ void AjmAt9Decoder::GetInfo(void* out_info) {
 
 std::tuple<u32, u32> AjmAt9Decoder::ProcessData(std::span<u8>& in_buf, SparseOutputBuffer& output,
                                                 AjmSidebandGaplessDecode& gapless,
-                                                u32 max_samples_per_channel) {
+                                                std::optional<u32> max_samples_per_channel) {
+    int ret = 0;
     int bytes_used = 0;
-    u32 ret = Atrac9Decode(m_handle, in_buf.data(), m_pcm_buffer.data(), &bytes_used);
+    switch (m_format) {
+    case AjmFormatEncoding::S16:
+        ret = Atrac9Decode(m_handle, in_buf.data(), reinterpret_cast<s16*>(m_pcm_buffer.data()),
+                           &bytes_used, True(m_flags & AjmAt9CodecFlags::NonInterleavedOutput));
+        break;
+    case AjmFormatEncoding::S32:
+        ret = Atrac9DecodeS32(m_handle, in_buf.data(), reinterpret_cast<s32*>(m_pcm_buffer.data()),
+                              &bytes_used, True(m_flags & AjmAt9CodecFlags::NonInterleavedOutput));
+        break;
+    case AjmFormatEncoding::Float:
+        ret =
+            Atrac9DecodeF32(m_handle, in_buf.data(), reinterpret_cast<float*>(m_pcm_buffer.data()),
+                            &bytes_used, True(m_flags & AjmAt9CodecFlags::NonInterleavedOutput));
+        break;
+    default:
+        UNREACHABLE();
+    }
     ASSERT_MSG(ret == At9Status::ERR_SUCCESS, "Atrac9Decode failed ret = {:#x}", ret);
     in_buf = in_buf.subspan(bytes_used);
 
     m_superframe_bytes_remain -= bytes_used;
-    std::span<s16> pcm_data{m_pcm_buffer};
 
+    u32 skipped_samples = 0;
     if (gapless.skipped_samples < gapless.skip_samples) {
-        const auto skipped_samples = std::min(u32(m_codec_info.frameSamples),
+        skipped_samples = std::min(u32(m_codec_info.frameSamples),
                                    u32(gapless.skip_samples - gapless.skipped_samples));
         gapless.skipped_samples += skipped_samples;
-        pcm_data = pcm_data.subspan(skipped_samples * m_codec_info.channels);
     }
 
-    const auto max_samples = max_samples_per_channel == std::numeric_limits<u32>::max()
-                                 ? max_samples_per_channel
-                                 : max_samples_per_channel * m_codec_info.channels;
+    const auto max_samples = max_samples_per_channel.has_value()
+                                 ? max_samples_per_channel.value() * m_codec_info.channels
+                                 : std::numeric_limits<u32>::max();
 
-    const auto pcm_size = std::min(u32(pcm_data.size()), max_samples);
-    const auto written = output.Write(pcm_data.subspan(0, pcm_size));
+    size_t samples_written = 0;
+    switch (m_format) {
+    case AjmFormatEncoding::S16:
+        samples_written = WriteOutputSamples<s16>(output, skipped_samples, max_samples);
+        break;
+    case AjmFormatEncoding::S32:
+        samples_written = WriteOutputSamples<s32>(output, skipped_samples, max_samples);
+        break;
+    case AjmFormatEncoding::Float:
+        samples_written = WriteOutputSamples<float>(output, skipped_samples, max_samples);
+        break;
+    default:
+        UNREACHABLE();
+    }
 
     m_num_frames += 1;
     if ((m_num_frames % m_codec_info.framesInSuperframe) == 0) {
@@ -85,7 +126,18 @@ std::tuple<u32, u32> AjmAt9Decoder::ProcessData(std::span<u8>& in_buf, SparseOut
         m_num_frames = 0;
     }
 
-    return {1, (written / m_codec_info.channels) / sizeof(s16)};
+    return {1, samples_written / m_codec_info.channels};
+}
+
+AjmSidebandFormat AjmAt9Decoder::GetFormat() {
+    return AjmSidebandFormat{
+        .num_channels = u32(m_codec_info.channels),
+        .channel_mask = GetChannelMask(u32(m_codec_info.channels)),
+        .sampl_freq = u32(m_codec_info.samplingRate),
+        .sample_encoding = m_format,
+        .bitrate = u32(m_codec_info.samplingRate * GetPointCodeSize() * 8),
+        .reserved = 0,
+    };
 }
 
 } // namespace Libraries::Ajm

src/core/libraries/ajm/ajm_at9.h

@@ -8,10 +8,18 @@
 
 #include "libatrac9.h"
 
+#include <span>
+
 namespace Libraries::Ajm {
 
 constexpr s32 ORBIS_AJM_DEC_AT9_MAX_CHANNELS = 8;
 
+enum AjmAt9CodecFlags : u32 {
+    ParseRiffHeader = 1 << 0,
+    NonInterleavedOutput = 1 << 8,
+};
+DECLARE_ENUM_FLAG_OPERATORS(AjmAt9CodecFlags)
+
 struct AjmSidebandDecAt9CodecInfo {
     u32 super_frame_size;
     u32 frames_in_super_frame;
@@ -20,22 +28,37 @@ struct AjmSidebandDecAt9CodecInfo {
 };
 
 struct AjmAt9Decoder final : AjmCodec {
-    explicit AjmAt9Decoder();
+    explicit AjmAt9Decoder(AjmFormatEncoding format, AjmAt9CodecFlags flags);
     ~AjmAt9Decoder() override;
 
     void Reset() override;
     void Initialize(const void* buffer, u32 buffer_size) override;
     void GetInfo(void* out_info) override;
+    AjmSidebandFormat GetFormat() override;
     std::tuple<u32, u32> ProcessData(std::span<u8>& input, SparseOutputBuffer& output,
-                                     AjmSidebandGaplessDecode& gapless, u32 max_samples) override;
+                                     AjmSidebandGaplessDecode& gapless,
+                                     std::optional<u32> max_samples) override;
 
 private:
+    u8 GetPointCodeSize();
+
+    template <class T>
+    size_t WriteOutputSamples(SparseOutputBuffer& output, u32 skipped_samples, u32 max_samples) {
+        std::span<T> pcm_data{reinterpret_cast<T*>(m_pcm_buffer.data()),
+                              m_pcm_buffer.size() / sizeof(T)};
+        pcm_data = pcm_data.subspan(skipped_samples * m_codec_info.channels);
+        const auto pcm_size = std::min(u32(pcm_data.size()), max_samples);
+        return output.Write(pcm_data.subspan(0, pcm_size));
+    }
+
+    const AjmFormatEncoding m_format;
+    const AjmAt9CodecFlags m_flags;
     void* m_handle{};
     u8 m_config_data[ORBIS_AT9_CONFIG_DATA_SIZE]{};
     u32 m_superframe_bytes_remain{};
     u32 m_num_frames{};
     Atrac9CodecInfo m_codec_info{};
-    std::vector<s16> m_pcm_buffer;
+    std::vector<u8> m_pcm_buffer;
 };
 
 } // namespace Libraries::Ajm

src/core/libraries/ajm/ajm_context.cpp

@@ -149,7 +149,6 @@ s32 AjmContext::InstanceCreate(AjmCodecType codec_type, AjmInstanceFlags flags,
     if (!IsRegistered(codec_type)) {
         return ORBIS_AJM_ERROR_CODEC_NOT_REGISTERED;
     }
-    ASSERT_MSG(flags.format == 0, "Only signed 16-bit PCM output is supported currently!");
     std::optional<u32> opt_index;
     {
         std::unique_lock lock(instances_mutex);

src/core/libraries/ajm/ajm_instance.cpp

@@ -9,14 +9,28 @@
 
 namespace Libraries::Ajm {
 
+constexpr int ORBIS_AJM_RESULT_NOT_INITIALIZED = 0x00000001;
+constexpr int ORBIS_AJM_RESULT_INVALID_DATA = 0x00000002;
+constexpr int ORBIS_AJM_RESULT_INVALID_PARAMETER = 0x00000004;
+constexpr int ORBIS_AJM_RESULT_PARTIAL_INPUT = 0x00000008;
+constexpr int ORBIS_AJM_RESULT_NOT_ENOUGH_ROOM = 0x00000010;
+constexpr int ORBIS_AJM_RESULT_STREAM_CHANGE = 0x00000020;
+constexpr int ORBIS_AJM_RESULT_TOO_MANY_CHANNELS = 0x00000040;
+constexpr int ORBIS_AJM_RESULT_UNSUPPORTED_FLAG = 0x00000080;
+constexpr int ORBIS_AJM_RESULT_SIDEBAND_TRUNCATED = 0x00000100;
+constexpr int ORBIS_AJM_RESULT_PRIORITY_PASSED = 0x00000200;
+constexpr int ORBIS_AJM_RESULT_CODEC_ERROR = 0x40000000;
+constexpr int ORBIS_AJM_RESULT_FATAL = 0x80000000;
+
 AjmInstance::AjmInstance(AjmCodecType codec_type, AjmInstanceFlags flags) : m_flags(flags) {
     switch (codec_type) {
     case AjmCodecType::At9Dec: {
-        m_codec = std::make_unique<AjmAt9Decoder>();
+        m_codec = std::make_unique<AjmAt9Decoder>(AjmFormatEncoding(flags.format),
+                                                  AjmAt9CodecFlags(flags.codec));
         break;
     }
     case AjmCodecType::Mp3Dec: {
-        m_codec = std::make_unique<AjmMp3Decoder>();
+        m_codec = std::make_unique<AjmMp3Decoder>(AjmFormatEncoding(flags.format));
         break;
     }
     default:
@@ -62,9 +76,10 @@ void AjmInstance::ExecuteJob(AjmJob& job) {
         auto in_size = in_buf.size();
         auto out_size = out_buf.Size();
         while (!in_buf.empty() && !out_buf.IsEmpty() && !IsGaplessEnd()) {
-            const u32 samples_remain = m_gapless.total_samples != 0
-                                           ? m_gapless.total_samples - m_gapless_samples
-                                           : std::numeric_limits<u32>::max();
+            const auto samples_remain =
+                m_gapless.total_samples != 0
+                    ? std::optional<u32>{m_gapless.total_samples - m_gapless_samples}
+                    : std::optional<u32>{};
             const auto [nframes, nsamples] =
                 m_codec->ProcessData(in_buf, out_buf, m_gapless, samples_remain);
             frames_decoded += nframes;
@@ -87,6 +102,9 @@ void AjmInstance::ExecuteJob(AjmJob& job) {
         m_gapless.skipped_samples = 0;
         m_codec->Reset();
     }
+    if (job.output.p_format != nullptr) {
+        *job.output.p_format = m_codec->GetFormat();
+    }
     if (job.output.p_gapless_decode != nullptr) {
         *job.output.p_gapless_decode = m_gapless;
     }

src/core/libraries/ajm/ajm_instance.h

@@ -14,19 +14,6 @@
 
 namespace Libraries::Ajm {
 
-constexpr int ORBIS_AJM_RESULT_NOT_INITIALIZED = 0x00000001;
-constexpr int ORBIS_AJM_RESULT_INVALID_DATA = 0x00000002;
-constexpr int ORBIS_AJM_RESULT_INVALID_PARAMETER = 0x00000004;
-constexpr int ORBIS_AJM_RESULT_PARTIAL_INPUT = 0x00000008;
-constexpr int ORBIS_AJM_RESULT_NOT_ENOUGH_ROOM = 0x00000010;
-constexpr int ORBIS_AJM_RESULT_STREAM_CHANGE = 0x00000020;
-constexpr int ORBIS_AJM_RESULT_TOO_MANY_CHANNELS = 0x00000040;
-constexpr int ORBIS_AJM_RESULT_UNSUPPORTED_FLAG = 0x00000080;
-constexpr int ORBIS_AJM_RESULT_SIDEBAND_TRUNCATED = 0x00000100;
-constexpr int ORBIS_AJM_RESULT_PRIORITY_PASSED = 0x00000200;
-constexpr int ORBIS_AJM_RESULT_CODEC_ERROR = 0x40000000;
-constexpr int ORBIS_AJM_RESULT_FATAL = 0x80000000;
-
 class SparseOutputBuffer {
 public:
     SparseOutputBuffer(std::span<std::span<u8>> chunks)
@@ -34,18 +21,19 @@ public:
 
     template <class T>
     size_t Write(std::span<T> pcm) {
-        size_t bytes_written = 0;
+        size_t samples_written = 0;
         while (!pcm.empty() && !IsEmpty()) {
             auto size = std::min(pcm.size() * sizeof(T), m_current->size());
             std::memcpy(m_current->data(), pcm.data(), size);
-            bytes_written += size;
-            pcm = pcm.subspan(size / sizeof(T));
+            const auto nsamples = size / sizeof(T);
+            samples_written += nsamples;
+            pcm = pcm.subspan(nsamples);
             *m_current = m_current->subspan(size);
             if (m_current->empty()) {
                 ++m_current;
             }
         }
-        return bytes_written;
+        return samples_written;
     }
 
     bool IsEmpty() {
@@ -65,11 +53,6 @@ private:
     std::span<std::span<u8>>::iterator m_current;
 };
 
-struct DecodeResult {
-    u32 bytes_consumed{};
-    u32 bytes_written{};
-};
-
 class AjmCodec {
 public:
     virtual ~AjmCodec() = default;
@@ -77,9 +60,10 @@ public:
     virtual void Initialize(const void* buffer, u32 buffer_size) = 0;
     virtual void Reset() = 0;
     virtual void GetInfo(void* out_info) = 0;
+    virtual AjmSidebandFormat GetFormat() = 0;
     virtual std::tuple<u32, u32> ProcessData(std::span<u8>& input, SparseOutputBuffer& output,
                                              AjmSidebandGaplessDecode& gapless,
-                                             u32 max_samples) = 0;
+                                             std::optional<u32> max_samples_per_channel) = 0;
 };
 
 class AjmInstance {
@@ -100,9 +84,6 @@ private:
     u32 m_total_samples{};
 
     std::unique_ptr<AjmCodec> m_codec;
-
-    // AjmCodecType codec_type;
-    // u32 index{};
 };
 
 } // namespace Libraries::Ajm

src/core/libraries/ajm/ajm_mp3.cpp

@@ -30,9 +30,27 @@ static constexpr std::array<s32, 2> UnkTable = {0x48, 0x90};
 
 SwrContext* swr_context{};
 
-AVFrame* ConvertAudioFrame(AVFrame* frame) {
+static AVSampleFormat AjmToAVSampleFormat(AjmFormatEncoding format) {
+    switch (format) {
+    case AjmFormatEncoding::S16:
+        return AV_SAMPLE_FMT_S16;
+    case AjmFormatEncoding::S32:
+        return AV_SAMPLE_FMT_S32;
+    case AjmFormatEncoding::Float:
+        return AV_SAMPLE_FMT_FLT;
+    default:
+        UNREACHABLE();
+    }
+}
+
+AVFrame* AjmMp3Decoder::ConvertAudioFrame(AVFrame* frame) {
+    AVSampleFormat format = AjmToAVSampleFormat(m_format);
+    if (frame->format == format) {
+        return frame;
+    }
+
     auto pcm16_frame = av_frame_clone(frame);
-    pcm16_frame->format = AV_SAMPLE_FMT_S16;
+    pcm16_frame->format = format;
 
     if (swr_context) {
         swr_free(&swr_context);
@@ -40,9 +58,9 @@ AVFrame* ConvertAudioFrame(AVFrame* frame) {
     }
     AVChannelLayout in_ch_layout = frame->ch_layout;
     AVChannelLayout out_ch_layout = pcm16_frame->ch_layout;
-    swr_alloc_set_opts2(&swr_context, &out_ch_layout, AV_SAMPLE_FMT_S16, frame->sample_rate,
-                        &in_ch_layout, AVSampleFormat(frame->format), frame->sample_rate, 0,
-                        nullptr);
+    swr_alloc_set_opts2(&swr_context, &out_ch_layout, AVSampleFormat(pcm16_frame->format),
+                        frame->sample_rate, &in_ch_layout, AVSampleFormat(frame->format),
+                        frame->sample_rate, 0, nullptr);
     swr_init(swr_context);
     const auto res = swr_convert_frame(swr_context, pcm16_frame, frame);
     if (res < 0) {
@@ -53,11 +71,9 @@ AVFrame* ConvertAudioFrame(AVFrame* frame) {
     return pcm16_frame;
 }
 
-AjmMp3Decoder::AjmMp3Decoder() {
-    m_codec = avcodec_find_decoder(AV_CODEC_ID_MP3);
-    ASSERT_MSG(m_codec, "MP3 m_codec not found");
-    m_parser = av_parser_init(m_codec->id);
-    ASSERT_MSG(m_parser, "Parser not found");
+AjmMp3Decoder::AjmMp3Decoder(AjmFormatEncoding format)
+    : m_format(format), m_codec(avcodec_find_decoder(AV_CODEC_ID_MP3)),
+      m_parser(av_parser_init(m_codec->id)) {
     AjmMp3Decoder::Reset();
 }
 
@@ -81,7 +97,7 @@ void AjmMp3Decoder::GetInfo(void* out_info) {
 
 std::tuple<u32, u32> AjmMp3Decoder::ProcessData(std::span<u8>& in_buf, SparseOutputBuffer& output,
                                                 AjmSidebandGaplessDecode& gapless,
-                                                u32 max_samples) {
+                                                std::optional<u32> max_samples_per_channel) {
     AVPacket* pkt = av_packet_alloc();
 
     int ret = av_parser_parse2(m_parser, m_codec_context, &pkt->data, &pkt->size, in_buf.data(),
@@ -109,24 +125,37 @@ std::tuple<u32, u32> AjmMp3Decoder::ProcessData(std::span<u8>& in_buf, SparseOut
             } else if (ret < 0) {
                 UNREACHABLE_MSG("Error during decoding");
             }
-            if (frame->format != AV_SAMPLE_FMT_S16) {
             frame = ConvertAudioFrame(frame);
-            }
 
             frames_decoded += 1;
-            samples_decoded += frame->nb_samples;
-            const auto size = frame->ch_layout.nb_channels * frame->nb_samples * sizeof(u16);
-            std::span<s16> pcm_data(reinterpret_cast<s16*>(frame->data[0]), size >> 1);
+            u32 skipped_samples = 0;
             if (gapless.skipped_samples < gapless.skip_samples) {
-                const auto skipped_samples = std::min(
-                    u32(frame->nb_samples), u32(gapless.skip_samples - gapless.skipped_samples));
+                skipped_samples = std::min(u32(frame->nb_samples),
+                                           u32(gapless.skip_samples - gapless.skipped_samples));
                 gapless.skipped_samples += skipped_samples;
-                pcm_data = pcm_data.subspan(skipped_samples * frame->ch_layout.nb_channels);
-                samples_decoded -= skipped_samples;
             }
 
-            const auto pcm_size = std::min(u32(pcm_data.size()), max_samples);
-            output.Write(pcm_data.subspan(0, pcm_size));
+            const auto max_samples =
+                max_samples_per_channel.has_value()
+                    ? max_samples_per_channel.value() * frame->ch_layout.nb_channels
+                    : std::numeric_limits<u32>::max();
+
+            switch (m_format) {
+            case AjmFormatEncoding::S16:
+                samples_decoded +=
+                    WriteOutputSamples<s16>(frame, output, skipped_samples, max_samples);
+                break;
+            case AjmFormatEncoding::S32:
+                samples_decoded +=
+                    WriteOutputSamples<s32>(frame, output, skipped_samples, max_samples);
+                break;
+            case AjmFormatEncoding::Float:
+                samples_decoded +=
+                    WriteOutputSamples<float>(frame, output, skipped_samples, max_samples);
+                break;
+            default:
+                UNREACHABLE();
+            }
 
             av_frame_free(&frame);
         }
@@ -163,4 +192,9 @@ int AjmMp3Decoder::ParseMp3Header(const u8* buf, u32 stream_size, int parse_ofl,
     return ORBIS_OK;
 }
 
+AjmSidebandFormat AjmMp3Decoder::GetFormat() {
+    LOG_ERROR(Lib_Ajm, "Unimplemented");
+    return AjmSidebandFormat{};
+};
+
 } // namespace Libraries::Ajm

src/core/libraries/ajm/ajm_mp3.h

@@ -7,11 +7,7 @@
 #include "core/libraries/ajm/ajm_instance.h"
 
 extern "C" {
-struct AVCodec;
-struct AVCodecContext;
-struct AVCodecParserContext;
-struct AVFrame;
-struct AVPacket;
+#include <libavcodec/avcodec.h>
 }
 
 namespace Libraries::Ajm {
@@ -54,19 +50,35 @@ struct AjmSidebandDecMp3CodecInfo {
 
 class AjmMp3Decoder : public AjmCodec {
 public:
-    explicit AjmMp3Decoder();
+    explicit AjmMp3Decoder(AjmFormatEncoding format);
     ~AjmMp3Decoder() override;
 
     void Reset() override;
     void Initialize(const void* buffer, u32 buffer_size) override {}
     void GetInfo(void* out_info) override;
+    AjmSidebandFormat GetFormat() override;
     std::tuple<u32, u32> ProcessData(std::span<u8>& input, SparseOutputBuffer& output,
-                                     AjmSidebandGaplessDecode& gapless, u32 max_samples) override;
+                                     AjmSidebandGaplessDecode& gapless,
+                                     std::optional<u32> max_samples_per_channel) override;
 
     static int ParseMp3Header(const u8* buf, u32 stream_size, int parse_ofl,
                               AjmDecMp3ParseFrame* frame);
 
 private:
+    template <class T>
+    size_t WriteOutputSamples(AVFrame* frame, SparseOutputBuffer& output, u32 skipped_samples,
+                              u32 max_samples) {
+        const auto size = frame->ch_layout.nb_channels * frame->nb_samples * sizeof(T);
+        std::span<T> pcm_data(reinterpret_cast<T*>(frame->data[0]), size >> 1);
+        pcm_data = pcm_data.subspan(skipped_samples * frame->ch_layout.nb_channels);
+        const auto pcm_size = std::min(u32(pcm_data.size()), max_samples);
+        const auto samples_written = output.Write(pcm_data.subspan(0, pcm_size));
+        return samples_written / frame->ch_layout.nb_channels;
+    }
+
+    AVFrame* ConvertAudioFrame(AVFrame* frame);
+
+    const AjmFormatEncoding m_format;
     const AVCodec* m_codec = nullptr;
     AVCodecContext* m_codec_context = nullptr;
     AVCodecParserContext* m_parser = nullptr;