avcodec/mediacodecdec: restructure mediacodec_receive_frame

The new logic follows a recommendation by @rcombs to use
dequeueInputBuffer with a timeout of 0 as a way to detect
whether the codec wants more data. The dequeued buffer index is
kept in MediaCodecDecContext until it can be used next.

A similar technique is also used by the Google's official media
player Exoplayer: see MediaCodecRenderer.feedInputBuffer().

Signed-off-by: Aman Gupta <aman@tmm1.net>
Signed-off-by: Matthieu Bouron <matthieu.bouron@gmail.com>

1 files changed, 16 insertions, 12 deletions

diff --git a/libavcodec/mediacodecdec_common.c b/libavcodec/mediacodecdec_common.c
index c0f0a6b983..887865a281 100644
--- a/libavcodec/mediacodecdec_common.c
+++ b/libavcodec/mediacodecdec_common.c
@@ -450,6 +450,7 @@ static int mediacodec_dec_flush_codec(AVCodecContext *avctx, MediaCodecDecContex
     s->eos = 0;
     atomic_fetch_add(&s->serial, 1);
     atomic_init(&s->hw_buffer_count, 0);
+    s->current_input_buffer = -1;
 
     status = ff_AMediaCodec_flush(codec);
     if (status < 0) {
@@ -477,6 +478,7 @@ int ff_mediacodec_dec_init(AVCodecContext *avctx, MediaCodecDecContext *s,
     atomic_init(&s->refcount, 1);
     atomic_init(&s->hw_buffer_count, 0);
     atomic_init(&s->serial, 1);
+    s->current_input_buffer = -1;
 
     pix_fmt = ff_get_format(avctx, pix_fmts);
     if (pix_fmt == AV_PIX_FMT_MEDIACODEC) {
@@ -561,16 +563,16 @@ fail:
 }
 
 int ff_mediacodec_dec_send(AVCodecContext *avctx, MediaCodecDecContext *s,
-                           AVPacket *pkt)
+                           AVPacket *pkt, bool wait)
 {
     int offset = 0;
     int need_draining = 0;
     uint8_t *data;
-    ssize_t index;
+    ssize_t index = s->current_input_buffer;
     size_t size;
     FFAMediaCodec *codec = s->codec;
     int status;
-    int64_t input_dequeue_timeout_us = INPUT_DEQUEUE_TIMEOUT_US;
+    int64_t input_dequeue_timeout_us = wait ? INPUT_DEQUEUE_TIMEOUT_US : 0;
     int64_t pts;
 
     if (s->flushing) {
@@ -588,17 +590,19 @@ int ff_mediacodec_dec_send(AVCodecContext *avctx, MediaCodecDecContext *s,
     }
 
     while (offset < pkt->size || (need_draining && !s->draining)) {
-
-        index = ff_AMediaCodec_dequeueInputBuffer(codec, input_dequeue_timeout_us);
-        if (ff_AMediaCodec_infoTryAgainLater(codec, index)) {
-            av_log(avctx, AV_LOG_TRACE, "No input buffer available, try again later\n");
-            break;
-        }
-
         if (index < 0) {
-            av_log(avctx, AV_LOG_ERROR, "Failed to dequeue input buffer (status=%zd)\n", index);
-            return AVERROR_EXTERNAL;
+            index = ff_AMediaCodec_dequeueInputBuffer(codec, input_dequeue_timeout_us);
+            if (ff_AMediaCodec_infoTryAgainLater(codec, index)) {
+                av_log(avctx, AV_LOG_TRACE, "No input buffer available, try again later\n");
+                break;
+            }
+
+            if (index < 0) {
+                av_log(avctx, AV_LOG_ERROR, "Failed to dequeue input buffer (status=%zd)\n", index);
+                return AVERROR_EXTERNAL;
+            }
         }
+        s->current_input_buffer = -1;
 
         data = ff_AMediaCodec_getInputBuffer(codec, index, &size);
         if (!data) {