unit UAudioDecoder_FFMpeg;

(*******************************************************************************

This unit is primarily based upon -
    http://www.dranger.com/ffmpeg/ffmpegtutorial_all.html

    and tutorial03.c

    http://www.inb.uni-luebeck.de/~boehme/using_libavcodec.html

*******************************************************************************)

interface

{$IFDEF FPC}
  {$MODE Delphi}
{$ENDIF}

{$I switches.inc}

//{$DEFINE DebugFFMpegDecode}

uses
  Classes,
  SysUtils,
  UMusic;

implementation

uses
  UIni,
  UMain,
  avcodec,     // FFMpeg Audio file decoding
  avformat,
  avutil,
  avio,        // used for url_ferror
  mathematics, // used for av_rescale_q
  SDL,
  ULog,
  UConfig;

type
  PPacketQueue = ^TPacketQueue;
  TPacketQueue = class
    private
      firstPkt,
      lastPkt    : PAVPacketList;
      nbPackets  : integer;
      size       : integer;
      mutex      : PSDL_Mutex;
      cond       : PSDL_Cond;
      quit       : boolean;

    public
      constructor Create();
      destructor Destroy(); override;

      function Put(pkt : PAVPacket): integer;
      function Get(var pkt: TAVPacket; block: boolean): integer;
      procedure Flush();
  end;

const
  MAX_AUDIOQ_SIZE = (5 * 16 * 1024);

var
  EOFPacket:   TAVPacket;
  FlushPacket: TAVPacket;

type
  PAudioBuffer = ^TAudioBuffer;
  TAudioBuffer = array[0 .. (AVCODEC_MAX_AUDIO_FRAME_SIZE * 3 div 2)-1] of byte;

type
  TFFMpegDecodeStream = class(TAudioDecodeStream)
    private
      _EOF: boolean; // end-of-stream flag
      _EOF_lock : PSDL_Mutex;

      internalLock : PSDL_Mutex;
      resumeCond   : PSDL_Cond;

      quitRequest : boolean;

      seekRequest: boolean;
      seekFlags  : integer;
      seekPos    : int64;

      parseThread: PSDL_Thread;
      packetQueue: TPacketQueue;

      formatInfo : TAudioFormatInfo;

      // FFMpeg internal data
      pFormatCtx     : PAVFormatContext;
      pCodecCtx      : PAVCodecContext;
      pCodec         : PAVCodec;
      ffmpegStreamIndex : Integer;
      ffmpegStream      : PAVStream;

      // state-vars for DecodeFrame
      pkt             : TAVPacket;
      audio_pkt_data  : PChar;
      audio_pkt_size  : integer;

      // state-vars for AudioCallback
      audio_buf_index : cardinal;
      audio_buf_size  : cardinal;
      audio_buf       : TAudioBuffer;

      procedure Lock(); {$IFDEF HasInline}inline;{$ENDIF}
      procedure Unlock(); {$IFDEF HasInline}inline;{$ENDIF}
      function GetLockMutex(): PSDL_Mutex; {$IFDEF HasInline}inline;{$ENDIF}

      procedure ParseAudio();
      function DecodeFrame(var buffer: TAudioBuffer; bufSize: integer): integer;
      procedure SetEOF(state: boolean);
    public
      constructor Create(pFormatCtx: PAVFormatContext;
                         pCodecCtx: PAVCodecContext; pCodec: PAVCodec;
                         ffmpegStreamIndex: Integer; ffmpegStream: PAVStream);
      destructor Destroy(); override;

      procedure Close();                     override;

      function GetLength(): real;            override;
      function GetAudioFormatInfo(): TAudioFormatInfo; override;
      function GetPosition: real;            override;
      procedure SetPosition(Time: real);     override;
      function IsEOF(): boolean;             override;

      function ReadData(Buffer: PChar; BufSize: integer): integer; override;
  end;

type
  TAudioDecoder_FFMpeg = class( TInterfacedObject, IAudioDecoder )
    private
      class function FindAudioStreamIndex(pFormatCtx : PAVFormatContext): integer;
    public
      function GetName: String;

      function InitializeDecoder(): boolean;
      function Open(const Filename: string): TAudioDecodeStream;
  end;

function DecodeThreadMain(streamPtr: Pointer): integer; cdecl; forward;

var
  singleton_AudioDecoderFFMpeg : IAudioDecoder;


{ TFFMpegDecodeStream }

constructor TFFMpegDecodeStream.Create(pFormatCtx: PAVFormatContext;
                   pCodecCtx: PAVCodecContext; pCodec: PAVCodec;
                   ffmpegStreamIndex : Integer; ffmpegStream: PAVStream);
begin
  inherited Create();

  packetQueue := TPacketQueue.Create();

  audio_pkt_data := nil;
  audio_pkt_size := 0;

  audio_buf_index := 0;
  audio_buf_size  := 0;

  FillChar(pkt, sizeof(TAVPacket), 0);

  Self.pFormatCtx := pFormatCtx;
  Self.pCodecCtx := pCodecCtx;
  Self.pCodec    := pCodec;
  Self.ffmpegStreamIndex := ffmpegStreamIndex;
  Self.ffmpegStream      := ffmpegStream;

  formatInfo := TAudioFormatInfo.Create(
    pCodecCtx^.channels,
    pCodecCtx^.sample_rate,
    // pCodecCtx^.sample_fmt not yet used by FFMpeg -> use FFMpeg's standard format
    asfS16
  );

  _EOF := false;
  _EOF_lock := SDL_CreateMutex();

  internalLock := SDL_CreateMutex();
  resumeCond := SDL_CreateCond();

  parseThread := SDL_CreateThread(@DecodeThreadMain, Self);
end;

destructor TFFMpegDecodeStream.Destroy();
begin
  Close();
  inherited;
end;

procedure TFFMpegDecodeStream.Close();
var
  status: integer;
begin
  Lock();
  quitRequest := true;
  SDL_CondSignal(resumeCond);
  Unlock();

  if (parseThread <> nil) then
  begin
    SDL_WaitThread(parseThread, status);
  end;

  // Close the codec
  if (pCodecCtx <> nil) then
  begin
    avcodec_close(pCodecCtx);
    pCodecCtx := nil;
  end;

  // Close the video file
  if (pFormatCtx <> nil) then
  begin
    av_close_input_file(pFormatCtx);
    pFormatCtx := nil;
  end;

  FreeAndNil(packetQueue);
  FreeAndNil(formatInfo);
end;

procedure TFFMpegDecodeStream.Lock();
begin
  SDL_mutexP(internalLock);
end;

procedure TFFMpegDecodeStream.Unlock();
begin
  SDL_mutexV(internalLock);
end;

function TFFMpegDecodeStream.GetLockMutex(): PSDL_Mutex;
begin
  Result := internalLock;
end;

function TFFMpegDecodeStream.GetLength(): real;
begin
  Result := pFormatCtx^.duration / AV_TIME_BASE;
end;

function TFFMpegDecodeStream.GetAudioFormatInfo(): TAudioFormatInfo;
begin
  Result := formatInfo;
end;

function TFFMpegDecodeStream.IsEOF(): boolean;
begin
  SDL_mutexP(_EOF_lock);
  Result := _EOF;
  SDL_mutexV(_EOF_lock);
end;

procedure TFFMpegDecodeStream.SetEOF(state: boolean);
begin
  SDL_mutexP(_EOF_lock);
  _EOF := state;
  SDL_mutexV(_EOF_lock);
end;

function TFFMpegDecodeStream.GetPosition(): real;
//var
//  bytes: integer;
begin
  // see: tutorial on synching (audio-clock)
  Result := 0;
end;

procedure TFFMpegDecodeStream.SetPosition(Time: real);
//var
//  bytes:    integer;
begin
  Lock();
  seekPos := Trunc(Time * AV_TIME_BASE);
  // FIXME: seek_flags = rel < 0 ? AVSEEK_FLAG_BACKWARD : 0
  seekFlags := 0;//AVSEEK_FLAG_BACKWARD;
  seekRequest := true;
  SDL_CondSignal(resumeCond);
  Unlock();
end;

function DecodeThreadMain(streamPtr: Pointer): integer; cdecl;
var
  stream: TFFMpegDecodeStream;
begin
  stream := TFFMpegDecodeStream(streamPtr);
  stream.ParseAudio();
  result := 0;
end;

procedure TFFMpegDecodeStream.ParseAudio();
var
  packet: TAVPacket;
  seekTarget: int64;
  eofState: boolean;
  pbIOCtx: PByteIOContext;
begin
  eofState := false;

  while (true) do
  begin
    Lock();
    // wait if end-of-file reached
    if (eofState) then
    begin
      if (not (seekRequest or quitRequest)) then
      begin
        // signal end-of-file
        packetQueue.put(@EOFPacket);
        // wait for reuse or destruction of stream
        repeat
          SDL_CondWait(resumeCond, GetLockMutex());
        until (seekRequest or quitRequest);
      end;
      eofState := false;
      SetEOF(false);
    end;

    if (quitRequest) then
    begin
      break;
    end;

    // handle seek-request
    if(seekRequest) then
    begin
      // TODO: Do we need this?
      //       The position is converted to AV_TIME_BASE and then to the stream-specific base.
      //       Why not convert to the stream-specific one from the beginning.
      seekTarget := av_rescale_q(seekPos, AV_TIME_BASE_Q, ffmpegStream^.time_base);
      if(av_seek_frame(pFormatCtx, ffmpegStreamIndex,
          seekTarget, seekFlags) < 0) then
      begin
        // this will crash in FPC due to a bug
        //Log.LogStatus({pFormatCtx^.filename +} ': error while seeking', 'UAudioDecoder_FFMpeg');
      end
      else
      begin
        packetQueue.Flush();
        packetQueue.Put(@FlushPacket);
      end;
      seekRequest := false;
    end;

    Unlock();

    
    if(packetQueue.size > MAX_AUDIOQ_SIZE) then
    begin
      SDL_Delay(10);
      continue;
    end;

    if(av_read_frame(pFormatCtx, packet) < 0) then
    begin
      {$IF (LIBAVFORMAT_VERSION_MAJOR >= 52)}
      pbIOCtx := pFormatCtx^.pb;
      {$ELSE}
      pbIOCtx := @pFormatCtx^.pb;
      {$IFEND}

      // check for end-of-file (eof is not an error)
      if(url_feof(pbIOCtx) <> 0) then
      begin
        {$IFDEF DebugFFMpegDecode}
        SafeWriteLn('feof');
        {$ENDIF}
        eofState := true;
        continue;
      end;

      // check for errors
      if(url_ferror(pbIOCtx) = 0) then
      begin
        {$IFDEF DebugFFMpegDecode}
        SafeWriteLn('Errorf');
        {$ENDIF}
        // no error -> wait for user input
        SDL_Delay(100);
        continue;
      end
      else
      begin
        // an error occured -> abort
        // TODO: eof or quit?
        eofState := true;
        continue;
      end;
    end;

    //SafeWriteLn( 'ffmpeg - av_read_frame' );

    if(packet.stream_index = ffmpegStreamIndex) then
    begin
      //SafeWriteLn( 'packet_queue_put' );
      packetQueue.put(@packet);
    end
    else
    begin
      av_free_packet(@packet);
    end;
  end;
end;

function TFFMpegDecodeStream.DecodeFrame(var buffer: TAudioBuffer; bufSize: integer): integer;
var
  len1,
  data_size: integer;
begin
  result := -1;

  if EOF then
    exit;

  while(true) do
  begin
    while (audio_pkt_size > 0) do
    begin
      //SafeWriteLn( 'got audio packet' );
      data_size := bufSize;

      {$IF LIBAVCODEC_VERSION >= 51030000} // 51.30.0
      len1 := avcodec_decode_audio2(pCodecCtx, @buffer,
                  data_size, audio_pkt_data, audio_pkt_size);
      {$ELSE}
      // FIXME: with avcodec_decode_audio a package could contain several frames
      //        this is not handled yet
      len1 := avcodec_decode_audio(pCodecCtx, @buffer,
                  data_size, audio_pkt_data, audio_pkt_size);
      {$IFEND}

      //SafeWriteLn('avcodec_decode_audio : ' + inttostr( len1 ));

      if(len1 < 0) then
      begin
        // if error, skip frame
        {$IFDEF DebugFFMpegDecode}
        SafeWriteLn( 'Skip audio frame' );
        {$ENDIF}
        audio_pkt_size := 0;
        break;
      end;

      Inc(audio_pkt_data, len1);
      Dec(audio_pkt_size, len1);

      if (data_size <= 0) then
      begin
        // no data yet, get more frames
        continue;
      end;

      // we have data, return it and come back for more later
      result := data_size;
      exit;
    end;

    if (pkt.data <> nil) then
    begin
      av_free_packet(@pkt);
    end;

    if (packetQueue.quit) then
      exit;

    if (packetQueue.Get(pkt, true) < 0) then
      exit;

    audio_pkt_data := PChar(pkt.data);
    audio_pkt_size := pkt.size;

    if (audio_pkt_data = PChar(FlushPacket.data)) then
    begin
      avcodec_flush_buffers(pCodecCtx);
      {$IFDEF DebugFFMpegDecode}
      SafeWriteLn('Flush');
      {$ENDIF}
      continue;
    end;

    // check for end-of-file
    if (audio_pkt_data = PChar(EOFPacket.data)) then
    begin
      // end-of-file reached -> set EOF-flag
      SetEOF(true);
      {$IFDEF DebugFFMpegDecode}
      SafeWriteLn('EOF');
      {$ENDIF}
      // note: buffer is not (even partially) filled -> no data to return
      exit;
    end;

    //SafeWriteLn( 'Audio Packet Size - ' + inttostr(audio_pkt_size) );
  end;
end;

function TFFMpegDecodeStream.ReadData(Buffer : PChar; BufSize: integer): integer;
var
  //outStream       : TFFMpegDecodeStream;
  len1,
  audio_size      : integer;
  len             : integer;
begin
  len := BufSize;
  result := -1;

  // end-of-file reached
  if EOF then
    exit;

  while (len > 0) do begin
    if (audio_buf_index >= audio_buf_size) then
    begin
      // we have already sent all our data; get more
      audio_size := DecodeFrame(audio_buf, sizeof(TAudioBuffer));
      //SafeWriteLn('audio_decode_frame : '+ inttostr(audio_size));

      if(audio_size < 0) then
      begin
        // if error, output silence
        audio_buf_size := 1024;
        FillChar(audio_buf, audio_buf_size, #0);
        //SafeWriteLn( 'Silence' );
      end
      else
      begin
        audio_buf_size := audio_size;
      end;
      audio_buf_index := 0;
    end;

    len1 := audio_buf_size - audio_buf_index;
    if (len1 > len) then
      len1 := len;

    Move(audio_buf[audio_buf_index], Buffer[0], len1);

    Dec(len, len1);
    Inc(Buffer, len1);
    Inc(audio_buf_index, len1);
  end;

  result := BufSize;
end;


{ TAudioDecoder_FFMpeg }

function TAudioDecoder_FFMpeg.GetName: String;
begin
  result := 'FFMpeg_Decoder';
end;

function TAudioDecoder_FFMpeg.InitializeDecoder: boolean;
begin
  //Log.LogStatus('InitializeDecoder', 'UAudioDecoder_FFMpeg');

  av_register_all();

  // init end-of-file package
  av_init_packet(EOFPacket);
  EOFPacket.data := Pointer(PChar('EOF'));

  // init flush package
  av_init_packet(FlushPacket);
  FlushPacket.data := Pointer(PChar('FLUSH'));

  result := true;
end;

class function TAudioDecoder_FFMpeg.FindAudioStreamIndex(pFormatCtx : PAVFormatContext): integer;
var
  i : integer;
  streamIndex: integer;
  stream : PAVStream;
begin
  // find the first audio stream
  streamIndex := -1;

  for i := 0 to pFormatCtx^.nb_streams-1 do
  begin
    //Log.LogStatus('aFormatCtx.streams[i] : ' + inttostr(i), 'UAudio_FFMpeg');
    stream := pFormatCtx^.streams[i];

    if ( stream.codec^.codec_type = CODEC_TYPE_AUDIO ) then
    begin
      //Log.LogStatus('Found Audio Stream', 'UAudio_FFMpeg');
      streamIndex := i;
      break;
    end;
  end;

  result := streamIndex;
end;

function TAudioDecoder_FFMpeg.Open(const Filename: string): TAudioDecodeStream;
var
  pFormatCtx     : PAVFormatContext;
  pCodecCtx      : PAVCodecContext;
  pCodec         : PAVCodec;
  ffmpegStreamID : Integer;
  ffmpegStream   : PAVStream;
//  wanted_spec,
  //csIndex        : integer;
  stream         : TFFMpegDecodeStream;
begin
  result := nil;

  if (not FileExists(Filename)) then
  begin
    Log.LogStatus('LoadSoundFromFile: Sound not found "' + Filename + '"', 'UAudio_FFMpeg');
    exit;
  end;

  // open audio file
  if (av_open_input_file(pFormatCtx, PChar(Filename), nil, 0, nil) > 0) then
    exit;

  // retrieve stream information
  if (av_find_stream_info(pFormatCtx) < 0) then
    exit;

  {$IFDEF DebugFFMpegDecode}
  dump_format(pFormatCtx, 0, pchar(Filename), 0);
  {$ENDIF}

  ffmpegStreamID := FindAudioStreamIndex(pFormatCtx);
  //Writeln('ID: ' + inttostr(ffmpegStreamID));
  if (ffmpegStreamID < 0) then
    exit;

  //Log.LogStatus('AudioStreamIndex is: '+ inttostr(ffmpegStreamID), 'UAudio_FFMpeg');

  ffmpegStream := pFormatCtx.streams[ffmpegStreamID];
  pCodecCtx := ffmpegStream^.codec;

  pCodec := avcodec_find_decoder(pCodecCtx^.codec_id);
  if (pCodec = nil) then
  begin
    Log.LogStatus('Unsupported codec!', 'UAudio_FFMpeg');
    exit;
  end;

  // set debug options
  pCodecCtx^.debug_mv := 0;
  pCodecCtx^.debug := 0;

  // detect bug-workarounds automatically
  pCodecCtx^.workaround_bugs := FF_BUG_AUTODETECT;

  // TODO: Not sure if these fields are for audio too
  //pCodecCtx^.lowres := lowres;
  //if (fast) then pCodecCtx^.flags2 := pCodecCtx^.flags2 or CODEC_FLAG2_FAST;
  //pCodecCtx^.skip_frame := skip_frame;
  //pCodecCtx^.skip_loop_filter := skip_loop_filter;
  //pCodecCtx^.error_resilience := error_resilience;
  //pCodecCtx^.error_concealment := error_concealment;

  if (avcodec_open(pCodecCtx, pCodec) < 0) then
  begin
    Log.LogStatus('avcodec_open failed!', 'UAudio_FFMpeg');
    exit;
  end;
  //WriteLn( 'Opened the codec' );

  stream := TFFMpegDecodeStream.Create(pFormatCtx, pCodecCtx, pCodec,
              ffmpegStreamID, ffmpegStream);

  result := stream;
end;


{ TPacketQueue }

constructor TPacketQueue.Create();
begin
  inherited;

  firstPkt := nil;
  lastPkt  := nil;
  nbPackets := 0;
  size := 0;

  mutex := SDL_CreateMutex();
  cond  := SDL_CreateCond();
end;

destructor TPacketQueue.Destroy();
begin
  Flush();
  SDL_DestroyMutex(mutex);
  SDL_DestroyCond(cond);
  inherited;
end;

function TPacketQueue.Put(pkt : PAVPacket): integer;
var
  pkt1 : PAVPacketList;
begin
  result := -1;

  if ((pkt <> @EOFPacket) and (pkt <> @FlushPacket)) then
    if (av_dup_packet(pkt) < 0) then
      exit;

  pkt1 := av_malloc(sizeof(TAVPacketList));
  if (pkt1 = nil) then
    exit;

  pkt1^.pkt  := pkt^;
  pkt1^.next := nil;


  SDL_LockMutex(Self.mutex);
  try

    if (Self.lastPkt = nil) then
      Self.firstPkt := pkt1
    else
      Self.lastPkt^.next := pkt1;

    Self.lastPkt := pkt1;
    inc(Self.nbPackets);

    //SafeWriteLn('Put: ' + inttostr(nbPackets));

    Self.size := Self.size + pkt1^.pkt.size;
    SDL_CondSignal(Self.cond);

  finally
    SDL_UnlockMutex(Self.mutex);
  end;

  result := 0;
end;

function TPacketQueue.Get(var pkt: TAVPacket; block: boolean): integer;
var
  pkt1 : PAVPacketList;
begin
  result := -1;

  SDL_LockMutex(Self.mutex);
  try
    while true do
    begin
      if (quit) then
        exit;

      pkt1 := Self.firstPkt;

      if (pkt1 <> nil) then
      begin
        Self.firstPkt := pkt1.next;
        if (Self.firstPkt = nil) then
          Self.lastPkt := nil;
        dec(Self.nbPackets);

        //SafeWriteLn('Get: ' + inttostr(nbPackets));

        Self.size := Self.size - pkt1^.pkt.size;
        pkt := pkt1^.pkt;
        av_free(pkt1);

        result := 1;
        break;
      end
      else
      if (not block) then
      begin
        result := 0;
        break;
      end
      else
      begin
        SDL_CondWait(Self.cond, Self.mutex);
      end;
    end;
  finally
    SDL_UnlockMutex(Self.mutex);
  end;
end;

procedure TPacketQueue.Flush();
var
  pkt, pkt1: PAVPacketList;
begin
  SDL_LockMutex(Self.mutex);

  pkt := Self.firstPkt;
  while(pkt <> nil) do
  begin
    pkt1 := pkt^.next;
    av_free_packet(@pkt^.pkt);
    // Note: param must be a pointer to a pointer!
    av_freep(@pkt);
    pkt := pkt1;
  end;
  Self.lastPkt := nil;
  Self.firstPkt := nil;
  Self.nbPackets := 0;
  Self.size := 0;

  SDL_UnlockMutex(Self.mutex);
end;


initialization
  singleton_AudioDecoderFFMpeg := TAudioDecoder_FFMpeg.create();

  //writeln( 'UAudioDecoder_FFMpeg - Register Decoder' );
  AudioManager.add( singleton_AudioDecoderFFMpeg );

finalization
  AudioManager.Remove( singleton_AudioDecoderFFMpeg );


end.