[FFmpeg-devel] [PATCH] avformat/aviobuf: fix broken logic in ffio_ensure_seekback()

[Paul B Mahol]

This removes big CPU overhead for demuxing chained ogg streams.

Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
 libavformat/aviobuf.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index a77517d712..ce9b7d59c9 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -996,20 +996,20 @@ int ffio_ensure_seekback(AVIOContext *s, int64_t buf_size)
     uint8_t *buffer;
     int max_buffer_size = s->max_packet_size ?
                           s->max_packet_size : IO_BUFFER_SIZE;
-    int filled = s->buf_end - s->buffer;
     ptrdiff_t checksum_ptr_offset = s->checksum_ptr ? s->checksum_ptr - s->buffer : -1;
 
-    buf_size += s->buf_ptr - s->buffer + max_buffer_size;
-
-    if (buf_size < filled || s->seekable || !s->read_packet)
+    if (buf_size <= s->buffer_size || s->seekable || !s->read_packet)
         return 0;
+    buf_size += s->buffer_size;
+    buf_size = FFMAX(buf_size, max_buffer_size);
+
     av_assert0(!s->write_flag);
 
     buffer = av_malloc(buf_size);
     if (!buffer)
         return AVERROR(ENOMEM);
 
-    memcpy(buffer, s->buffer, filled);
+    memcpy(buffer, s->buffer, s->buffer_size);
     av_free(s->buffer);
     s->buf_ptr = buffer + (s->buf_ptr - s->buffer);
     s->buf_end = buffer + (s->buf_end - s->buffer);
-- 
2.17.1