From 0871ae1a930122f7124358a0ce3caf81876913a9 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Sun, 25 May 2008 22:20:39 +0000
Subject: [PATCH] Make av_fifo*_read() ignore the available amount of data.
 This is more efficient as in practice the check is redundant most of the
 time. Callers which do not know if enough data is available have to check it
 with av_fifo_size(). Doing the check in *read() means the caller has no
 choice to skip the check when its known to be redundant. Also the return
 value was never documented in a public header so changing it should not break
 the API. Besides this fixes the case where read() failed on a 100% full fifo.

Originally committed as revision 13404 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 ffmpeg.c              | 7 ++++---
 libavformat/mpegenc.c | 4 ++--
 libavutil/fifo.c      | 8 --------
 3 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/ffmpeg.c b/ffmpeg.c
index dc53f34c34..544927956f 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -592,10 +592,12 @@ static void do_audio_out(AVFormatContext *s,
 
         frame_bytes = enc->frame_size * 2 * enc->channels;
 
-        while (av_fifo_read(&ost->fifo, audio_buf, frame_bytes) == 0) {
+        while (av_fifo_size(&ost->fifo) >= frame_bytes) {
             AVPacket pkt;
             av_init_packet(&pkt);
 
+            av_fifo_read(&ost->fifo, audio_buf, frame_bytes);
+
             //FIXME pass ost->sync_opts as AVFrame.pts in avcodec_encode_audio()
 
             ret = avcodec_encode_audio(enc, audio_out, audio_out_size,
@@ -1385,9 +1387,8 @@ static int output_packet(AVInputStream *ist, int ist_index,
                             if(fifo_bytes > 0 && enc->codec->capabilities & CODEC_CAP_SMALL_LAST_FRAME) {
                                 int fs_tmp = enc->frame_size;
                                 enc->frame_size = fifo_bytes / (2 * enc->channels);
-                                if(av_fifo_read(&ost->fifo, (uint8_t *)samples, fifo_bytes) == 0) {
+                                av_fifo_read(&ost->fifo, (uint8_t *)samples, fifo_bytes);
                                     ret = avcodec_encode_audio(enc, bit_buffer, bit_buffer_size, samples);
-                                }
                                 enc->frame_size = fs_tmp;
                             }
                             if(ret <= 0) {
diff --git a/libavformat/mpegenc.c b/libavformat/mpegenc.c
index 05c72cd1e7..c96ffd1684 100644
--- a/libavformat/mpegenc.c
+++ b/libavformat/mpegenc.c
@@ -913,8 +913,8 @@ static int flush_packet(AVFormatContext *ctx, int stream_index,
         }
 
         /* output data */
-        if(av_fifo_generic_read(&stream->fifo, payload_size - stuffing_size, &put_buffer, ctx->pb) < 0)
-            return -1;
+        assert(payload_size - stuffing_size <= av_fifo_size(&stream->fifo));
+        av_fifo_generic_read(&stream->fifo, payload_size - stuffing_size, &put_buffer, ctx->pb);
         stream->bytes_to_iframe -= payload_size - stuffing_size;
     }else{
         payload_size=
diff --git a/libavutil/fifo.c b/libavutil/fifo.c
index 19ec13e63d..f2ace514bd 100644
--- a/libavutil/fifo.c
+++ b/libavutil/fifo.c
@@ -45,9 +45,6 @@ int av_fifo_size(AVFifoBuffer *f)
     return size;
 }
 
-/**
- * Get data from the fifo (returns -1 if not enough data).
- */
 int av_fifo_read(AVFifoBuffer *f, uint8_t *buf, int buf_size)
 {
     return av_fifo_generic_read(f, buf_size, NULL, buf);
@@ -97,13 +94,8 @@ int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void
 }
 
 
-/** get data from the fifo (return -1 if not enough data) */
 int av_fifo_generic_read(AVFifoBuffer *f, int buf_size, void (*func)(void*, void*, int), void* dest)
 {
-    int size = av_fifo_size(f);
-
-    if (size < buf_size)
-        return -1;
     do {
         int len = FFMIN(f->end - f->rptr, buf_size);
         if(func) func(dest, f->rptr, len);