avpacket: use AVBuffer to allow refcounting the packets.

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

This breaks ABI.

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"
@@ -892,17 +893,23 @@ 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.
@@ -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.
@@ -3454,6 +3469,21 @@ 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.

libavcodec/avpacket.c

@@ -22,16 +22,26 @@
 #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);
  pkt->data = NULL;
  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;
 

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++;

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 */