Universal Audio Class

Based on my implementation in sceAac https://github.com/hrydgard/ppsspp/pull/5836
I've created a class AuCtx included in My SimpleAudioDec.cpp/.h which aims at providing a standard easy implementation to support all codecs in ffmpeg.
Here, I also completely re-code sceMp3 file with this class to give an example how to use this class, and it has solved all mp3 issues I've observed in the current master.
Tests on different freq and channels mp3 audios as:
Miku custom BGM (48kHz, stereo), Hanayaka Nari Wa ga Ichizoku(32kHz, mono, a little fast but better than before now), downstreet panic (44.1kHz, stereo), and learn jp09(44.1kHz, stero) are just all right.
Especially, I am very glad to see that Miku's Custom BGMs have no repetition issues in first tone any more and no longer stopped in the first second neither. :)
We will come into a new age to fast support new audio formats from now on I hope :P

Core/HW/SimpleAudioDec.cpp

@@ -61,7 +61,7 @@ bool SimpleAudio::GetAudioCodecID(int audioType){
 }
 
 SimpleAudio::SimpleAudio(int audioType)
-: codec_(0), codecCtx_(0), swrCtx_(0), audioType(audioType), outSamples(0){
+: codec_(0), codecCtx_(0), swrCtx_(0), audioType(audioType), outSamples(0), wanted_resample_freq(44100){
 #ifdef USE_FFMPEG
 	avcodec_register_all();
 	av_register_all();
@@ -103,7 +103,7 @@ SimpleAudio::SimpleAudio(int audioType)
 
 
 SimpleAudio::SimpleAudio(u32 ctxPtr, int audioType)
-: codec_(0), codecCtx_(0), swrCtx_(0), ctxPtr(ctxPtr), audioType(audioType), outSamples(0){
+: codec_(0), codecCtx_(0), swrCtx_(0), ctxPtr(ctxPtr), audioType(audioType), outSamples(0), wanted_resample_freq(44100){
 #ifdef USE_FFMPEG
 	avcodec_register_all();
 	av_register_all();
@@ -136,6 +136,7 @@ SimpleAudio::SimpleAudio(u32 ctxPtr, int audioType)
 	AVDictionary *opts = 0;
 	if (avcodec_open2(codecCtx_, codec_, &opts) < 0) {
 		ERROR_LOG(ME, "Failed to open codec");
+		av_dict_free(&opts);
 		return;
 	}
 
@@ -143,6 +144,35 @@ SimpleAudio::SimpleAudio(u32 ctxPtr, int audioType)
 #endif  // USE_FFMPEG
 }
 
+bool SimpleAudio::ResetCodecCtx(int channels, int samplerate){
+#ifdef USE_FFMPEG
+	if (codecCtx_)
+		avcodec_close(codecCtx_);
+
+	// Find decoder
+	codec_ = avcodec_find_decoder(audioCodecId);
+	if (!codec_) {
+		// Eh, we shouldn't even have managed to compile. But meh.
+		ERROR_LOG(ME, "This version of FFMPEG does not support AV_CODEC_ctx for audio (%s). Update your submodule.", GetCodecName(audioType));
+		return false;
+	}
+
+	codecCtx_->channels = channels;
+	codecCtx_->channel_layout = channels==2?AV_CH_LAYOUT_STEREO:AV_CH_LAYOUT_MONO;
+	codecCtx_->sample_rate = samplerate;
+	// Open codec
+	AVDictionary *opts = 0;
+	if (avcodec_open2(codecCtx_, codec_, &opts) < 0) {
+		ERROR_LOG(ME, "Failed to open codec");
+		av_dict_free(&opts);
+		return false;
+	}
+	av_dict_free(&opts);
+	return true;
+#endif
+	return false;
+}
+
 SimpleAudio::~SimpleAudio() {
 #ifdef USE_FFMPEG
 	if (frame_)
@@ -195,7 +225,7 @@ bool SimpleAudio::Decode(void* inbuf, int inbytes, uint8_t *outbuf, int *outbyte
 			swrCtx_,
 			wanted_channel_layout,
 			AV_SAMPLE_FMT_S16,
-			44100,
+			wanted_resample_freq,
 			dec_channel_layout,
 			codecCtx_->sample_fmt,
 			codecCtx_->sample_rate,
@@ -242,6 +272,10 @@ int SimpleAudio::getSourcePos(){
 	return srcPos;
 }
 
+void SimpleAudio::setResampleFrequency(int freq){
+	wanted_resample_freq = freq;
+}
+
 void AudioClose(SimpleAudio **ctx) {
 #ifdef USE_FFMPEG
 	delete *ctx;
@@ -269,7 +303,6 @@ u32 AuCtx::sceAuDecode(u32 pcmAddr)
 
 	auto inbuff = Memory::GetPointer(AuBuf);
 	auto outbuf = Memory::GetPointer(PCMBuf);
-	memset(outbuf, 0, PCMBufSize);
 	u32 outpcmbufsize = 0;
 
 	// move inbuff to writePos of buffer
@@ -287,7 +320,6 @@ u32 AuCtx::sceAuDecode(u32 pcmAddr)
 				readPos -= AuBufAvailable;
 			}
 			AuBufAvailable = 0;
-			//break;
 		}
 		// count total output pcm size 
 		outpcmbufsize += pcmframesize;
@@ -306,60 +338,17 @@ u32 AuCtx::sceAuDecode(u32 pcmAddr)
 
 	Memory::Write_U32(PCMBuf, pcmAddr);
 
-	return outpcmbufsize;
-}
-
-/*
-// return output pcm size, <0 error
-u32 AuCtx::sceAuDecode(u32 pcmAddr)
-{
-	if (!Memory::IsValidAddress(pcmAddr)){
-		ERROR_LOG(ME, "%s: output bufferAddress %08x is invalctx", __FUNCTION__, pcmAddr);
-		return -1;
+	// if we got zero pcm, and we still haven't reach endPos. 
+	// some game like "Miku" will stop playing if we return 0, but some others will recharge buffer.
+	// so we did a hack here, clear output buff and just return a nonzero value to continue 
+	if (outpcmbufsize == 0 && readPos < endPos){
+		// clear output buffer will avoid noise
+		memset(outbuf, 0, PCMBufSize);
+		return FF_INPUT_BUFFER_PADDING_SIZE; // return a padding size seems very good and almost unsensible latency.
 	}
 
-	auto inbuff = Memory::GetPointer(AuBuf);
-	auto outbuf = Memory::GetPointer(PCMBuf);
-	memset(outbuf, 0, PCMBufSize);
-	u32 outpcmbufsize = 0;
-
-	// move inbuff to writePos of buffer
-	inbuff += writePos;
-
-	// decode frames in AuBuf and output into PCMBuf if it is not exceed
-	if (AuBufAvailable > 0 && outpcmbufsize < PCMBufSize){
-		int pcmframesize;
-		// decode
-		decoder->Decode(inbuff, AuBufAvailable, outbuf, &pcmframesize);
-		if (pcmframesize == 0){
-			// no output pcm, we have either no data or no enough data to decode
-			// move back audio source readPos to the begin of the last incomplete frame if we not start looping and reset available AuBuf
-			if (readPos > startPos) { // this means we are not begin to loop yet
-				readPos -= AuBufAvailable;
-			}
-			AuBufAvailable = 0;
-			//break;
-		}
-		// count total output pcm size 
-		outpcmbufsize += pcmframesize;
-		// count total output samples
-		SumDecodedSamples += decoder->getOutSamples();
-		// move inbuff position to next frame
-		int srcPos = decoder->getSourcePos();
-		inbuff += srcPos;
-		// decrease available AuBuf
-		AuBufAvailable -= srcPos;
-		// modify the writePos value
-		writePos += srcPos;
-		// move outbuff position to the current end of output 
-		outbuf += pcmframesize;
-	}
-
-	Memory::Write_U32(PCMBuf, pcmAddr);
-
 	return outpcmbufsize;
 }
-*/
 
 u32 AuCtx::sceAuGetLoopNum()
 {
@@ -446,4 +435,8 @@ int AuCtx::sceAuGetSamplingRate(){
 u32 AuCtx::sceAuResetPlayPositionByFrame(int position){
 	readPos = position;
 	return 0;
-}
+}
+
+int AuCtx::sceAuGetVersion(){
+	return Version;
+}