From 7ae7543de287dbdf0dca24321dc014849bb775f6 Mon Sep 17 00:00:00 2001
From: Romain Vimont <rom@rom1v.com>
Date: Tue, 28 Feb 2023 21:20:28 +0100
Subject: [PATCH] Call avcodec_receive_frame() in a loop

Since in scrcpy a video packet passed to avcodec_send_packet() is always
a complete video frame, it is sufficient to call avcodec_receive_frame()
exactly once.

In practice, it also works for audio packets: the decoder produces
exactly 1 frame for 1 input packet.

In theory, it is an implementation detail though, so
avcodec_receive_frame() should be called in a loop.
---
 app/src/decoder.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/app/src/decoder.c b/app/src/decoder.c
index 33acc0da..a4e70418 100644
--- a/app/src/decoder.c
+++ b/app/src/decoder.c
@@ -121,8 +121,19 @@ sc_decoder_push(struct sc_decoder *decoder, const AVPacket *packet) {
              decoder->name, ret);
         return false;
     }
-    ret = avcodec_receive_frame(decoder->codec_ctx, decoder->frame);
-    if (!ret) {
+
+    for (;;) {
+        ret = avcodec_receive_frame(decoder->codec_ctx, decoder->frame);
+        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
+            break;
+        }
+
+        if (ret) {
+            LOGE("Decoder '%s', could not receive video frame: %d",
+                 decoder->name, ret);
+            return false;
+        }
+
         // a frame was received
         bool ok = push_frame_to_sinks(decoder, decoder->frame);
         // A frame lost should not make the whole pipeline fail. The error, if
@@ -130,11 +141,8 @@ sc_decoder_push(struct sc_decoder *decoder, const AVPacket *packet) {
         (void) ok;
 
         av_frame_unref(decoder->frame);
-    } else if (ret != AVERROR(EAGAIN)) {
-        LOGE("Decoder '%s', could not receive video frame: %d",
-             decoder->name, ret);
-        return false;
     }
+
     return true;
 }