[FFmpeg-devel] [PATCH 1/2] avcodec/cbs: add ff_cbs_read_buf()

[FFmpeg-devel] [PATCH 1/2] avcodec/cbs: add ff_cbs_read_buf()

[James Almer]

To take a reference from an existing buffer outside of AVPackets.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavcodec/cbs.c | 10 +++++++++-
 libavcodec/cbs.h | 11 +++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c
index c0f6c62d20..b26e3ea3de 100644
--- a/libavcodec/cbs.c
+++ b/libavcodec/cbs.c
@@ -261,7 +261,7 @@ static int cbs_fill_fragment_data(CodedBitstreamFragment *frag,
 
 static int cbs_read_data(CodedBitstreamContext *ctx,
                          CodedBitstreamFragment *frag,
-                         AVBufferRef *buf,
+                         const AVBufferRef *buf,
                          const uint8_t *data, size_t size,
                          int header)
 {
@@ -334,6 +334,14 @@ int CBS_FUNC(read)(CodedBitstreamContext *ctx,
     return cbs_read_data(ctx, frag, NULL,
                          data, size, 0);
 }
+
+int CBS_FUNC(read_buf)(CodedBitstreamContext *ctx,
+                       CodedBitstreamFragment *frag,
+                       const AVBufferRef *buf)
+{
+    return cbs_read_data(ctx, frag, buf,
+                         buf->data, buf->size, 0);
+}
 #endif
 
 #if CBS_WRITE
diff --git a/libavcodec/cbs.h b/libavcodec/cbs.h
index 47818d5c12..8b503fdcce 100644
--- a/libavcodec/cbs.h
+++ b/libavcodec/cbs.h
@@ -381,6 +381,17 @@ int CBS_FUNC(read)(CodedBitstreamContext *ctx,
                 CodedBitstreamFragment *frag,
                 const uint8_t *data, size_t size);
 
+/**
+ * Read a bitstream from a memory region into a fragment, then
+ * split into units and decompose.
+ *
+ * This acts identical to ff_cbs_read() with the addition of an
+ * AVBufferRef backing the data.
+ */
+int CBS_FUNC(read_buf)(CodedBitstreamContext *ctx,
+                       CodedBitstreamFragment *frag,
+                       const AVBufferRef *buf);
+
 
 /**
  * Write the content of the fragment to its own internal buffer.
-- 
2.49.0

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[FFmpeg-devel] [PATCH 2/2] avcodec/apv_parser: use ff_cbs_read_buf()

[James Almer]

Removes an unecessary data copying.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavcodec/apv_parser.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/libavcodec/apv_parser.c b/libavcodec/apv_parser.c
index bd1894146c..25b80285a5 100644
--- a/libavcodec/apv_parser.c
+++ b/libavcodec/apv_parser.c
@@ -16,6 +16,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/avassert.h"
+#include "libavutil/buffer.h"
+
 #include "avcodec.h"
 #include "apv.h"
 #include "cbs.h"
@@ -34,6 +37,11 @@ static const enum AVPixelFormat apv_format_table[5][5] = {
     { AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA444P10, AV_PIX_FMT_YUVA444P12, AV_PIX_FMT_GRAY14, AV_PIX_FMT_YUVA444P16 },
 };
 
+static void dummy_free(void *opaque, uint8_t *data)
+{
+    av_assert0(opaque == data);
+}
+
 static int parse(AVCodecParserContext *s,
                  AVCodecContext *avctx,
                  const uint8_t **poutbuf, int *poutbuf_size,
@@ -41,6 +49,7 @@ static int parse(AVCodecParserContext *s,
 {
     APVParseContext *p = s->priv_data;
     CodedBitstreamFragment *au = &p->au;
+    AVBufferRef *ref = NULL;
     int ret;
 
     *poutbuf      = buf;
@@ -48,7 +57,12 @@ static int parse(AVCodecParserContext *s,
 
     p->cbc->log_ctx = avctx;
 
-    ret = ff_cbs_read(p->cbc, au, buf, buf_size);
+    ref = av_buffer_create((uint8_t *)buf, buf_size, dummy_free,
+                           (void *)buf, AV_BUFFER_FLAG_READONLY);
+    if (!ref)
+        goto end;
+
+    ret = ff_cbs_read_buf(p->cbc, au, ref);
     if (ret < 0) {
         av_log(avctx, AV_LOG_ERROR, "Failed to parse access unit.\n");
         goto end;
@@ -92,6 +106,9 @@ static int parse(AVCodecParserContext *s,
 
 end:
     ff_cbs_fragment_reset(au);
+    if (ref)
+        av_assert1(av_buffer_get_ref_count(ref) == 1);
+    av_buffer_unref(&ref);
     p->cbc->log_ctx = NULL;
 
     return buf_size;
-- 
2.49.0

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Re: [FFmpeg-devel] [PATCH 1/2] avcodec/cbs: add ff_cbs_read_buf()

[James Almer]

[-- Attachment #1.1.1: Type: text/plain, Size: 324 bytes --]

On 5/1/2025 10:44 PM, James Almer wrote:
> To take a reference from an existing buffer outside of AVPackets.
> 
> Signed-off-by: James Almer <jamrial@gmail.com>
> ---
>   libavcodec/cbs.c | 10 +++++++++-
>   libavcodec/cbs.h | 11 +++++++++++
>   2 files changed, 20 insertions(+), 1 deletion(-)

Will apply set.


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