[FFmpeg-devel] [RFC][GSoC][PATCH v1 5/6] avformat/utils: add av_packet_buffer_filter to filter packet_buffer

[Hongcheng Zhong]

From: spartazhc <spartazhc at gmail.com>

Add av_packet_buffer_filter to remove AVPackets whose stream_index is not
in st_index list. st_index has length of AVMEDIA_TYPE_NB, contains
the stream_index of all these media types.

Generally s->internal->packet_buffer may have pkts from different
stream, and stream_index will be used to discard pkt that is not
needed. But in case of abr, several streams may pass the stream_index
check. So we need a function to remove AVPackets not needed in pktl
added by hls_read_header.

v1 fixed:
1. rename function name *_clean to *_filter
2. fix memory leak in ff_packet_buffer_filter
3. update the doc

Signed-off-by: spartazhc <spartazhc at gmail.com>
---
 libavformat/avformat.h | 12 ++++++++++
 libavformat/internal.h | 16 +++++++++++++
 libavformat/utils.c    | 54 ++++++++++++++++++++++++++++++++++++++++++
 libavformat/version.h  |  2 +-
 4 files changed, 83 insertions(+), 1 deletion(-)

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index e91e7f1d33..c796fd0391 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -2474,6 +2474,18 @@ int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int
  */
 int avformat_flush(AVFormatContext *s);
 
+/**
+ * Filter the packet buffer list of the AVFormatContext, remove the AVPackets
+ * do not need according to st_index.
+ * Only filter the packet_buffer list.
+ *
+ * @param s media file handle
+ * @param st_index the stream_index list which is needed
+ *        st_index has length of AVMEDIA_TYPE_NB
+ *        in index AVMEDIA_TYPE_XXX contains the stream_index needed of type XXX
+ */
+int av_packet_buffer_filter(AVFormatContext *s, int *st_index);
+
 /**
  * Start playing a network-based stream (e.g. RTSP stream) at the
  * current position.
diff --git a/libavformat/internal.h b/libavformat/internal.h
index 17a6ab07d3..58ebcb2e35 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -772,6 +772,22 @@ int ff_packet_list_get(AVPacketList **head, AVPacketList **tail,
  */
 void ff_packet_list_free(AVPacketList **head, AVPacketList **tail);
 
+/**
+ * Remove the AVPackets do not need in the packet buffer list.
+ * For each type in AVMediaType, at most keep one stream and
+ * the others will be removed.
+ *
+ * @param head List head element
+ * @param tail List tail element
+ * @param st_index the stream_index list which is needed
+ *        st_index has length of AVMEDIA_TYPE_NB
+ *        in index AVMEDIA_TYPE_XXX contains the stream_index needed of type XXX
+ * @return 0 on success. Success is guaranteed
+ *         if the packet list is not empty.
+ */
+int ff_packet_buffer_filter(AVPacketList **head, AVPacketList **tail,
+                            int *st_index);
+
 void avpriv_register_devices(const AVOutputFormat * const o[], const AVInputFormat * const i[]);
 
 #endif /* AVFORMAT_INTERNAL_H */
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 807d9f10cb..7674e4ea3d 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1565,6 +1565,60 @@ int ff_packet_list_get(AVPacketList **pkt_buffer,
     return 0;
 }
 
+/**
+ * return 1 if needed
+ */
+static int ff_check_st_index(int st, int *st_index)
+{
+    for (int i = 0; i < AVMEDIA_TYPE_NB; ++i) {
+        if (st_index[i] == st)
+            return 1;
+    }
+    return 0;
+}
+
+int ff_packet_buffer_filter(AVPacketList **pkt_buffer,
+                         AVPacketList **pkt_buffer_end,
+                         int           *st_index)
+{
+    AVPacketList *pktl, *pktn;
+    av_assert0(*pkt_buffer);
+    pktl = *pkt_buffer;
+    pktn = pktl->next;
+
+    /* num >= 2 */
+    while (pktn) {
+        if (!ff_check_st_index(pktn->pkt.stream_index, st_index)) {
+            av_packet_unref(&pktn->pkt);
+            pktl->next = pktn->next;
+            av_freep(&pktn);
+            pktn = pktl->next;
+        } else {
+            pktl = pktn;
+            pktn = pktn->next;
+        }
+    }
+    *pkt_buffer_end = pktl;
+    /* first one*/
+    pktl = *pkt_buffer;
+    if (!ff_check_st_index(pktl->pkt.stream_index, st_index)) {
+        av_packet_unref(&pktl->pkt);
+        *pkt_buffer = pktl->next;
+        if (!pktl->next)
+            *pkt_buffer_end = NULL;
+        av_freep(&pktl);
+    }
+
+    return 0;
+}
+
+int av_packet_buffer_filter(AVFormatContext *s, int *st_index)
+{
+    int ret = ff_packet_buffer_filter(&s->internal->packet_buffer,
+                                   &s->internal->packet_buffer_end, st_index);
+    return ret;
+}
+
 static int64_t ts_to_samples(AVStream *st, int64_t ts)
 {
     return av_rescale(ts, st->time_base.num * st->codecpar->sample_rate, st->time_base.den);
diff --git a/libavformat/version.h b/libavformat/version.h
index 75c03fde0a..33cebed85e 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -32,7 +32,7 @@
 // Major bumping may affect Ticket5467, 5421, 5451(compatibility with Chromium)
 // Also please add any ticket numbers that you believe might be affected here
 #define LIBAVFORMAT_VERSION_MAJOR  58
-#define LIBAVFORMAT_VERSION_MINOR  48
+#define LIBAVFORMAT_VERSION_MINOR  49
 #define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
-- 
2.27.0