[FFmpeg-devel] [PATCH] Use AVBufferPool in MOV

[Arnaud Masserann]

Most demuxers allocate a new buffer for each packet.
For MOV, this can be problematic, because of some high-bitrate
codecs like ProRes/HAPQ/NotchLC.

Use pools of buffer instead.

For some test media, demuxing goes from 20ms/frame to 11ms/frame,
close to the perf of ReadFile (10ms/frame), making it possible
to read the media at 60Hz.

Signed-off-by: Arnaud Masserann <Arnaud1602 at gmail.com>
---
 libavformat/avformat.h | 12 ++++++++++++
 libavformat/isom.h     |  2 ++
 libavformat/mov.c      | 20 ++++++++++++++++++--
 libavformat/utils.c    | 29 +++++++++++++++++++++++++++++
 4 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 56c1c80289..25f2e59b22 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -440,6 +440,18 @@ int av_get_packet(AVIOContext *s, AVPacket *pkt, int size);
  */
 int av_append_packet(AVIOContext *s, AVPacket *pkt, int size);
 
+
+/**
+ * Like av_get_packet, but allocates the AVPacket's buffer from a pool.
+ *
+ * @param s    associated IO context
+ * @param pool the pool of buffers; must be initialized with a sufficient size
+ * @param pkt packet
+ * @param size desired payload size
+ * @return >0 (read size) if OK, AVERROR_xxx otherwise
+ */
+int av_get_pooled_packet(AVIOContext *s, AVBufferPool* pool, AVPacket *pkt, int size);
+
 /*************************************************/
 /* input/output formats */
 
diff --git a/libavformat/isom.h b/libavformat/isom.h
index 4723397048..c608f30e04 100644
--- a/libavformat/isom.h
+++ b/libavformat/isom.h
@@ -273,6 +273,8 @@ typedef struct MOVStreamContext {
     } cenc;
 
     struct IAMFDemuxContext *iamf;
+
+    AVBufferPool* pools[32];
 } MOVStreamContext;
 
 typedef struct HEIFItem {
diff --git a/libavformat/mov.c b/libavformat/mov.c
index a2333ac1fd..2668bdf78f 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -9583,6 +9583,7 @@ static void mov_free_encryption_index(MOVEncryptionIndex **index) {
 static void mov_free_stream_context(AVFormatContext *s, AVStream *st)
 {
     MOVStreamContext *sc = st->priv_data;
+    int i;
 
     if (!sc || --sc->refcount) {
         st->priv_data = NULL;
@@ -9639,6 +9640,9 @@ static void mov_free_stream_context(AVFormatContext *s, AVStream *st)
         ff_iamf_read_deinit(sc->iamf);
 #endif
     av_freep(&sc->iamf);
+
+    for (i = 0; i < FF_ARRAY_ELEMS(sc->pools); i++)
+        av_buffer_pool_uninit(&sc->pools[i]);
 }
 
 static int mov_read_close(AVFormatContext *s)
@@ -10544,6 +10548,16 @@ static int mov_finalize_packet(AVFormatContext *s, AVStream *st, AVIndexEntry *s
     return 0;
 }
 
+static AVBufferPool *mov_pool_get(AVBufferPool* pools[32], int size)
+{
+    int index = av_log2(size + AV_INPUT_BUFFER_PADDING_SIZE);
+    if (!pools[index]) {
+        int pool_size = 2 << index;
+        pools[index] = av_buffer_pool_init(pool_size, NULL);
+    }
+    return pools[index];
+}
+
 static int mov_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     MOVContext *mov = s->priv_data;
@@ -10617,8 +10631,10 @@ static int mov_read_packet(AVFormatContext *s, AVPacket *pkt)
                 return FFERROR_REDO;
         }
 #endif
-        else
-            ret = av_get_packet(sc->pb, pkt, sample->size);
+        else{
+            AVBufferPool* pool = mov_pool_get(sc->pools, sample->size);
+            ret = av_get_pooled_packet(sc->pb, pool, pkt, sample->size);
+        }
         if (ret < 0) {
             if (should_retry(sc->pb, ret)) {
                 mov_current_sample_dec(sc);
diff --git a/libavformat/utils.c b/libavformat/utils.c
index e9ded627ad..869e97c089 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -104,6 +104,35 @@ FF_ENABLE_DEPRECATION_WARNINGS
     return append_packet_chunked(s, pkt, size);
 }
 
+int av_get_pooled_packet(AVIOContext *s, AVBufferPool* pool, AVPacket *pkt, int size)
+{
+#if FF_API_INIT_PACKET
+FF_DISABLE_DEPRECATION_WARNINGS
+    av_init_packet(pkt);
+    pkt->data = NULL;
+    pkt->size = 0;
+FF_ENABLE_DEPRECATION_WARNINGS
+#else
+    av_packet_unref(pkt);
+#endif
+    pkt->pos  = avio_tell(s);
+
+    if(!pool)
+        return AVERROR(ENOMEM);
+
+    pkt->buf = av_buffer_pool_get(pool);;
+    if(!pkt->buf)
+        return AVERROR(ENOMEM);
+
+    if(pkt->buf->size < size){
+        av_packet_unref(pkt); // TODO test this
+        return AVERROR(ENOMEM);
+    }
+
+    return append_packet_chunked(s, pkt, size);
+}
+
+
 int av_append_packet(AVIOContext *s, AVPacket *pkt, int size)
 {
     if (!pkt->size)
-- 
2.38.1.windows.1