From 2754f05b11e14e6ce98c7aa0dcb06fa583910f9d Mon Sep 17 00:00:00 2001
From: bnnm <bananaman255@gmail.com>
Date: Wed, 30 Nov 2016 23:48:49 +0100
Subject: [PATCH] Move FFmpeg looping to ffmpeg_decoder for further changes
 (cleanup)

---
 src/coding/coding.h         |  3 +++
 src/coding/ffmpeg_decoder.c | 52 +++++++++++++++++++++++++++++++++++++
 src/vgmstream.c             | 48 +---------------------------------
 3 files changed, 56 insertions(+), 47 deletions(-)

diff --git a/src/coding/coding.h b/src/coding/coding.h
index 02e1142f..6b8eeaff 100644
--- a/src/coding/coding.h
+++ b/src/coding/coding.h
@@ -111,6 +111,9 @@ void decode_at3plus(VGMSTREAM *vgmstream,
 #ifdef VGM_USE_FFMPEG
 void decode_ffmpeg(VGMSTREAM *stream,
                    sample * outbuf, int32_t samples_to_do, int channels);
+
+void seek_ffmpeg(VGMSTREAM *vgmstream, int32_t num_sample);
+
 #endif
 
 void decode_acm(ACMStream * acm, sample * outbuf,
diff --git a/src/coding/ffmpeg_decoder.c b/src/coding/ffmpeg_decoder.c
index a6f0a5d6..eaecf32e 100644
--- a/src/coding/ffmpeg_decoder.c
+++ b/src/coding/ffmpeg_decoder.c
@@ -247,4 +247,56 @@ end:
     data->endOfAudio = endOfAudio;
 }
 
+
+void seek_ffmpeg(VGMSTREAM *vgmstream, int32_t num_sample) {
+    ffmpeg_codec_data *data = (ffmpeg_codec_data *) vgmstream->codec_data;
+    int64_t ts;
+
+#ifndef VGM_USE_FFMPEG_ACCURATE_LOOPING
+    /* Seek to loop start by timestamp (closest frame) + adjust skipping some samples */
+    /* FFmpeg seeks by ts by design (since not all containers can accurately skip to a frame). */
+    /* TODO: this seems to be off by +-1 frames in some cases */
+    ts = num_sample;
+    if (ts >= data->sampleRate * 2) {
+        data->samplesToDiscard = data->sampleRate * 2;
+        ts -= data->samplesToDiscard;
+    }
+    else {
+        data->samplesToDiscard = (int)ts;
+        ts = 0;
+    }
+
+    /* todo fix this properly */
+    if (data->totalFrames) {
+        data->framesRead = (int)ts;
+        ts = data->framesRead * (data->formatCtx->duration) / data->totalFrames;
+    } else {
+        data->samplesToDiscard = num_sample;
+        data->framesRead = 0;
+        ts = 0;
+    }
+
+    avformat_seek_file(data->formatCtx, -1, ts - 1000, ts, ts, AVSEEK_FLAG_ANY);
+    avcodec_flush_buffers(data->codecCtx);
+#endif /* ifndef VGM_USE_FFMPEG_ACCURATE_LOOPING */
+
+#ifdef VGM_USE_FFMPEG_ACCURATE_LOOPING
+    /* Start from 0 and discard samples until loop_start for accurate looping (slower but not too noticeable) */
+    /* We could also seek by offset (AVSEEK_FLAG_BYTE) to the frame closest to the loop then discard
+     *  some samples, which is fast but would need calculations per format / when frame size is not constant */
+    data->samplesToDiscard = num_sample;
+    data->framesRead = 0;
+    ts = 0;
+
+    avformat_seek_file(data->formatCtx, -1, ts, ts, ts, AVSEEK_FLAG_ANY);
+    avcodec_flush_buffers(data->codecCtx);
+#endif /* ifdef VGM_USE_FFMPEG_ACCURATE_LOOPING */
+
+    data->readNextPacket = 1;
+    data->bytesConsumedFromDecodedFrame = INT_MAX;
+    data->endOfStream = 0;
+    data->endOfAudio = 0;
+
+}
+
 #endif
diff --git a/src/vgmstream.c b/src/vgmstream.c
index ef063f2f..f464e407 100644
--- a/src/vgmstream.c
+++ b/src/vgmstream.c
@@ -1789,53 +1789,7 @@ int vgmstream_do_loop(VGMSTREAM * vgmstream) {
             }
 #ifdef VGM_USE_FFMPEG
             if (vgmstream->coding_type==coding_FFmpeg) {
-                ffmpeg_codec_data *data = (ffmpeg_codec_data *)(vgmstream->codec_data);
-                int64_t ts;
-
-#ifndef VGM_USE_FFMPEG_ACCURATE_LOOPING
-                /* Seek to loop start by timestamp (closest frame) + adjust skipping some samples */
-                /* FFmpeg seeks by ts by design (since not all containers can accurately skip to a frame). */
-                /* TODO: this seems to be off by +-1 frames in some cases */
-                ts = vgmstream->loop_start_sample;
-                if (ts >= data->sampleRate * 2) {
-                    data->samplesToDiscard = data->sampleRate * 2;
-                    ts -= data->samplesToDiscard;
-                }
-                else {
-                    data->samplesToDiscard = (int)ts;
-                    ts = 0;
-                }
-
-                /* todo fix this properly */
-                if (data->totalFrames) {
-                    data->framesRead = (int)ts;
-                    ts = data->framesRead * (data->formatCtx->duration) / data->totalFrames;
-                } else {
-                    data->samplesToDiscard = vgmstream->loop_start_sample;
-                    data->framesRead = 0;
-                    ts = 0;
-                }
-
-                avformat_seek_file(data->formatCtx, -1, ts - 1000, ts, ts, AVSEEK_FLAG_ANY);
-                avcodec_flush_buffers(data->codecCtx);
-#endif /* ifndef VGM_USE_FFMPEG_ACCURATE_LOOPING */
-
-#ifdef VGM_USE_FFMPEG_ACCURATE_LOOPING
-                /* Start from 0 and discard samples until loop_start for accurate looping (slower but not too noticeable) */
-                /* We could also seek by offset (AVSEEK_FLAG_BYTE) to the frame closest to the loop then discard
-                 *  some samples, which is fast but would need calculations per format / when frame size is not constant */
-                data->samplesToDiscard = vgmstream->loop_start_sample;
-                data->framesRead = 0;
-                ts = 0;
-
-                avformat_seek_file(data->formatCtx, -1, ts, ts, ts, AVSEEK_FLAG_ANY);
-                avcodec_flush_buffers(data->codecCtx);
-#endif /* ifdef VGM_USE_FFMPEG_ACCURATE_LOOPING */
-
-                data->readNextPacket = 1;
-                data->bytesConsumedFromDecodedFrame = INT_MAX;
-                data->endOfStream = 0;
-                data->endOfAudio = 0;
+                seek_ffmpeg(vgmstream, vgmstream->loop_start_sample);
             }
 #endif /* VGM_USE_FFMPEG */
 #if defined(VGM_USE_MP4V2) && defined(VGM_USE_FDKAAC)