avpacket: use AVBuffer to allow refcounting the packets.

This will allow us to avoid copying the packets in many cases.

This breaks ABI.

4 files changed, 145 insertions, 39 deletions

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 120bfbcaae..1eba5e51bb 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -29,6 +29,7 @@
 #include <errno.h>
 #include "libavutil/samplefmt.h"
 #include "libavutil/avutil.h"
+#include "libavutil/buffer.h"
 #include "libavutil/cpu.h"
 #include "libavutil/dict.h"
 #include "libavutil/log.h"
@@ -892,18 +893,24 @@ enum AVPacketSideDataType {
  * ABI. Thus it may be allocated on stack and no new fields can be added to it
  * without libavcodec and libavformat major bump.
  *
- * The semantics of data ownership depends on the destruct field.
- * If it is set, the packet data is dynamically allocated and is valid
- * indefinitely until av_free_packet() is called (which in turn calls the
- * destruct callback to free the data). If destruct is not set, the packet data
- * is typically backed by some static buffer somewhere and is only valid for a
- * limited time (e.g. until the next read call when demuxing).
+ * The semantics of data ownership depends on the buf or destruct (deprecated)
+ * fields. If either is set, the packet data is dynamically allocated and is
+ * valid indefinitely until av_free_packet() is called (which in turn calls
+ * av_buffer_unref()/the destruct callback to free the data). If neither is set,
+ * the packet data is typically backed by some static buffer somewhere and is
+ * only valid for a limited time (e.g. until the next read call when demuxing).
  *
  * The side data is always allocated with av_malloc() and is freed in
  * av_free_packet().
  */
 typedef struct AVPacket {
     /**
+     * A reference to the reference-counted buffer where the packet data is
+     * stored.
+     * May be NULL, then the packet data is not reference-counted.
+     */
+    AVBufferRef *buf;
+    /**
      * Presentation timestamp in AVStream->time_base units; the time at which
      * the decompressed packet will be presented to the user.
      * Can be AV_NOPTS_VALUE if it is not stored in the file.
@@ -942,8 +949,12 @@ typedef struct AVPacket {
      * Equals next_pts - this_pts in presentation order.
      */
     int   duration;
+#if FF_API_DESTRUCT_PACKET
+    attribute_deprecated
     void  (*destruct)(struct AVPacket *);
+    attribute_deprecated
     void  *priv;
+#endif
     int64_t pos;                            ///< byte position in stream, -1 if unknown
 
     /**
@@ -3413,10 +3424,14 @@ void avsubtitle_free(AVSubtitle *sub);
  * @{
  */
 
+#if FF_API_DESTRUCT_PACKET
 /**
  * Default packet destructor.
+ * @deprecated use the AVBuffer API instead
  */
+attribute_deprecated
 void av_destruct_packet(AVPacket *pkt);
+#endif
 
 /**
  * Initialize optional fields of a packet with default values.
@@ -3455,6 +3470,21 @@ void av_shrink_packet(AVPacket *pkt, int size);
 int av_grow_packet(AVPacket *pkt, int grow_by);
 
 /**
+ * Initialize a reference-counted packet from av_malloc()ed data.
+ *
+ * @param pkt packet to be initialized. This function will set the data, size,
+ *        buf and destruct fields, all others are left untouched.
+ * @param data Data allocated by av_malloc() to be used as packet data. If this
+ *        function returns successfully, the data is owned by the underlying AVBuffer.
+ *        The caller may not access the data through other means.
+ * @param size size of data in bytes, without the padding. I.e. the full buffer
+ *        size is assumed to be size + FF_INPUT_BUFFER_PADDING_SIZE.
+ *
+ * @return 0 on success, a negative AVERROR on error
+ */
+int av_packet_from_data(AVPacket *pkt, uint8_t *data, int size);
+
+/**
  * @warning This is a hack - the packet memory allocation stuff is broken. The
  * packet is allocated if it was not really allocated.
  */
diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
index c26fb8e35c..c94f28272a 100644
--- a/libavcodec/avpacket.c
+++ b/libavcodec/avpacket.c
@@ -22,9 +22,11 @@
 #include <string.h>
 
 #include "libavutil/avassert.h"
+#include "libavutil/common.h"
 #include "libavutil/mem.h"
 #include "avcodec.h"
 
+#if FF_API_DESTRUCT_PACKET
 void av_destruct_packet(AVPacket *pkt)
 {
     av_free(pkt->data);
@@ -32,6 +34,14 @@ void av_destruct_packet(AVPacket *pkt)
     pkt->size = 0;
 }
 
+/* a dummy destruct callback for the callers that assume AVPacket.destruct ==
+ * NULL => static data */
+static void dummy_destruct_packet(AVPacket *pkt)
+{
+    av_assert0(0);
+}
+#endif
+
 void av_init_packet(AVPacket *pkt)
 {
     pkt->pts                  = AV_NOPTS_VALUE;
@@ -41,27 +51,35 @@ void av_init_packet(AVPacket *pkt)
     pkt->convergence_duration = 0;
     pkt->flags                = 0;
     pkt->stream_index         = 0;
+#if FF_API_DESTRUCT_PACKET
     pkt->destruct             = NULL;
+#endif
+    pkt->buf                  = NULL;
     pkt->side_data            = NULL;
     pkt->side_data_elems      = 0;
 }
 
 int av_new_packet(AVPacket *pkt, int size)
 {
-    uint8_t *data = NULL;
-    if ((unsigned)size < (unsigned)size + FF_INPUT_BUFFER_PADDING_SIZE)
-        data = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
-    if (data) {
-        memset(data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
-    } else
-        size = 0;
+    AVBufferRef *buf = NULL;
+
+    if ((unsigned)size >= (unsigned)size + FF_INPUT_BUFFER_PADDING_SIZE)
+        return AVERROR(EINVAL);
+
+    av_buffer_realloc(&buf, size + FF_INPUT_BUFFER_PADDING_SIZE);
+    if (!buf)
+        return AVERROR(ENOMEM);
+
+    memset(buf->data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
 
     av_init_packet(pkt);
-    pkt->data     = data;
+    pkt->buf      = buf;
+    pkt->data     = buf->data;
     pkt->size     = size;
-    pkt->destruct = av_destruct_packet;
-    if (!data)
-        return AVERROR(ENOMEM);
+#if FF_API_DESTRUCT_PACKET
+    pkt->destruct = dummy_destruct_packet;
+#endif
+
     return 0;
 }
 
@@ -75,33 +93,71 @@ void av_shrink_packet(AVPacket *pkt, int size)
 
 int av_grow_packet(AVPacket *pkt, int grow_by)
 {
-    void *new_ptr;
+    int new_size;
     av_assert0((unsigned)pkt->size <= INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE);
     if (!pkt->size)
         return av_new_packet(pkt, grow_by);
     if ((unsigned)grow_by >
         INT_MAX - (pkt->size + FF_INPUT_BUFFER_PADDING_SIZE))
         return -1;
-    new_ptr = av_realloc(pkt->data,
-                         pkt->size + grow_by + FF_INPUT_BUFFER_PADDING_SIZE);
-    if (!new_ptr)
-        return AVERROR(ENOMEM);
-    pkt->data  = new_ptr;
+
+    new_size = pkt->size + grow_by + FF_INPUT_BUFFER_PADDING_SIZE;
+    if (pkt->buf) {
+        int ret = av_buffer_realloc(&pkt->buf, new_size);
+        if (ret < 0)
+            return ret;
+    } else {
+        pkt->buf = av_buffer_alloc(new_size);
+        if (!pkt->buf)
+            return AVERROR(ENOMEM);
+        memcpy(pkt->buf->data, pkt->data, FFMIN(pkt->size, pkt->size + grow_by));
+#if FF_API_DESTRUCT_PACKET
+        pkt->destruct = dummy_destruct_packet;
+#endif
+    }
+    pkt->data  = pkt->buf->data;
     pkt->size += grow_by;
     memset(pkt->data + pkt->size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
+
     return 0;
 }
 
-#define DUP_DATA(dst, src, size, padding)                               \
+int av_packet_from_data(AVPacket *pkt, uint8_t *data, int size)
+{
+    if (size >= INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE)
+        return AVERROR(EINVAL);
+
+    pkt->buf = av_buffer_create(data, size + FF_INPUT_BUFFER_PADDING_SIZE,
+                                av_buffer_default_free, NULL, 0);
+    if (!pkt->buf)
+        return AVERROR(ENOMEM);
+
+    pkt->data = data;
+    pkt->size = size;
+#if FF_API_DESTRUCT_PACKET
+    pkt->destruct = dummy_destruct_packet;
+#endif
+
+    return 0;
+}
+
+#define ALLOC_MALLOC(data, size) data = av_malloc(size)
+#define ALLOC_BUF(data, size)                \
+do {                                         \
+    av_buffer_realloc(&pkt->buf, size);      \
+    data = pkt->buf ? pkt->buf->data : NULL; \
+} while (0)
+
+#define DUP_DATA(dst, src, size, padding, ALLOC)                        \
     do {                                                                \
         void *data;                                                     \
         if (padding) {                                                  \
             if ((unsigned)(size) >                                      \
                 (unsigned)(size) + FF_INPUT_BUFFER_PADDING_SIZE)        \
                 goto failed_alloc;                                      \
-            data = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);      \
+            ALLOC(data, size + FF_INPUT_BUFFER_PADDING_SIZE);           \
         } else {                                                        \
-            data = av_malloc(size);                                     \
+            ALLOC(data, size);                                          \
         }                                                               \
         if (!data)                                                      \
             goto failed_alloc;                                          \
@@ -116,30 +172,36 @@ int av_dup_packet(AVPacket *pkt)
 {
     AVPacket tmp_pkt;
 
-    if (pkt->destruct == NULL && pkt->data) {
+    if (!pkt->buf && pkt->data
+#if FF_API_DESTRUCT_PACKET
+        && !pkt->destruct
+#endif
+        ) {
         tmp_pkt = *pkt;
 
         pkt->data      = NULL;
         pkt->side_data = NULL;
-        DUP_DATA(pkt->data, tmp_pkt.data, pkt->size, 1);
-        pkt->destruct = av_destruct_packet;
+        DUP_DATA(pkt->data, tmp_pkt.data, pkt->size, 1, ALLOC_BUF);
+#if FF_API_DESTRUCT_PACKET
+        pkt->destruct = dummy_destruct_packet;
+#endif
 
         if (pkt->side_data_elems) {
             int i;
 
             DUP_DATA(pkt->side_data, tmp_pkt.side_data,
-                     pkt->side_data_elems * sizeof(*pkt->side_data), 0);
+                     pkt->side_data_elems * sizeof(*pkt->side_data), 0, ALLOC_MALLOC);
             memset(pkt->side_data, 0,
                    pkt->side_data_elems * sizeof(*pkt->side_data));
             for (i = 0; i < pkt->side_data_elems; i++)
                 DUP_DATA(pkt->side_data[i].data, tmp_pkt.side_data[i].data,
-                         tmp_pkt.side_data[i].size, 1);
+                         tmp_pkt.side_data[i].size, 1, ALLOC_MALLOC);
         }
     }
     return 0;
 
 failed_alloc:
-    av_destruct_packet(pkt);
+    av_free_packet(pkt);
     return AVERROR(ENOMEM);
 }
 
@@ -148,8 +210,13 @@ void av_free_packet(AVPacket *pkt)
     if (pkt) {
         int i;
 
-        if (pkt->destruct)
+        if (pkt->buf)
+            av_buffer_unref(&pkt->buf);
+#if FF_API_DESTRUCT_PACKET
+        else if (pkt->destruct)
             pkt->destruct(pkt);
+        pkt->destruct = NULL;
+#endif
         pkt->data            = NULL;
         pkt->size            = 0;
 
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 2a78f7fc0e..091d34c158 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -887,13 +887,19 @@ int ff_alloc_packet(AVPacket *avpkt, int size)
         return AVERROR(EINVAL);
 
     if (avpkt->data) {
+        AVBufferRef *buf = avpkt->buf;
+#if FF_API_DESTRUCT_PACKET
         void *destruct = avpkt->destruct;
+#endif
 
         if (avpkt->size < size)
             return AVERROR(EINVAL);
 
         av_init_packet(avpkt);
+#if FF_API_DESTRUCT_PACKET
         avpkt->destruct = destruct;
+#endif
+        avpkt->buf      = buf;
         avpkt->size     = size;
         return 0;
     } else {
@@ -1020,9 +1026,9 @@ int attribute_align_arg avcodec_encode_audio2(AVCodecContext *avctx,
         }
 
         if (!user_packet && avpkt->size) {
-            uint8_t *new_data = av_realloc(avpkt->data, avpkt->size);
-            if (new_data)
-                avpkt->data = new_data;
+            ret = av_buffer_realloc(&avpkt->buf, avpkt->size);
+            if (ret >= 0)
+                avpkt->data = avpkt->buf->data;
         }
 
         avctx->frame_number++;
@@ -1197,9 +1203,9 @@ int attribute_align_arg avcodec_encode_video2(AVCodecContext *avctx,
             avpkt->pts = avpkt->dts = frame->pts;
 
         if (!user_packet && avpkt->size) {
-            uint8_t *new_data = av_realloc(avpkt->data, avpkt->size);
-            if (new_data)
-                avpkt->data = new_data;
+            ret = av_buffer_realloc(&avpkt->buf, avpkt->size);
+            if (ret >= 0)
+                avpkt->data = avpkt->buf->data;
         }
 
         avctx->frame_number++;
diff --git a/libavcodec/version.h b/libavcodec/version.h
index 5b65c2d6a0..78fcdbfaae 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -100,5 +100,8 @@
 #ifndef FF_API_DEINTERLACE
 #define FF_API_DEINTERLACE       (LIBAVCODEC_VERSION_MAJOR < 56)
 #endif
+#ifndef FF_API_DESTRUCT_PACKET
+#define FF_API_DESTRUCT_PACKET   (LIBAVCODEC_VERSION_MAJOR < 56)
+#endif
 
 #endif /* AVCODEC_VERSION_H */