[FFmpeg-devel] [PATCH 2/2] avcodec/libdav1d: use a custom picture allocator

[James Almer]

Replaces the libdav1d internal allocator. It uses an AVBufferPool to reduce the
amount of allocated buffers.
About 5% speed up when decoding 720p or higher streams.

Signed-off-by: James Almer <jamrial at gmail.com>
---
get_buffer2() can't be used for this decoder, as there's no guarantee the buffers
it returns will respect the constrains specified by libdav1d.

 libavcodec/libdav1d.c | 72 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 65 insertions(+), 7 deletions(-)

diff --git a/libavcodec/libdav1d.c b/libavcodec/libdav1d.c
index 459bbae687..855c27db7f 100644
--- a/libavcodec/libdav1d.c
+++ b/libavcodec/libdav1d.c
@@ -22,6 +22,7 @@
 #include <dav1d/dav1d.h>
 
 #include "libavutil/avassert.h"
+#include "libavutil/imgutils.h"
 #include "libavutil/opt.h"
 
 #include "avcodec.h"
@@ -31,12 +32,21 @@
 typedef struct Libdav1dContext {
     AVClass *class;
     Dav1dContext *c;
+    AVBufferPool *pool;
+    int pool_size;
 
     Dav1dData data;
     int tile_threads;
     int apply_grain;
 } Libdav1dContext;
 
+static const enum AVPixelFormat pix_fmt[][3] = {
+    [DAV1D_PIXEL_LAYOUT_I400] = { AV_PIX_FMT_GRAY8,   AV_PIX_FMT_GRAY10,    AV_PIX_FMT_GRAY12 },
+    [DAV1D_PIXEL_LAYOUT_I420] = { AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV420P10, AV_PIX_FMT_YUV420P12 },
+    [DAV1D_PIXEL_LAYOUT_I422] = { AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV422P12 },
+    [DAV1D_PIXEL_LAYOUT_I444] = { AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV444P10, AV_PIX_FMT_YUV444P12 },
+};
+
 static void libdav1d_log_callback(void *opaque, const char *fmt, va_list vl)
 {
     AVCodecContext *c = opaque;
@@ -44,6 +54,57 @@ static void libdav1d_log_callback(void *opaque, const char *fmt, va_list vl)
     av_vlog(c, AV_LOG_ERROR, fmt, vl);
 }
 
+static int libdav1d_picture_allocator(Dav1dPicture *p, void *cookie) {
+    Libdav1dContext *dav1d = cookie;
+    enum AVPixelFormat format = pix_fmt[p->p.layout][p->seq_hdr->hbd];
+    int ret, linesize[4], h = FFALIGN(p->p.h, 128);
+    uint8_t *aligned_ptr, *data[4];
+    AVBufferRef *buf;
+
+    ret = av_image_fill_arrays(data, linesize, NULL, format, FFALIGN(p->p.w, 128),
+                               h, DAV1D_PICTURE_ALIGNMENT);
+    if (ret < 0)
+        return ret;
+
+    if (ret != dav1d->pool_size) {
+        av_buffer_pool_uninit(&dav1d->pool);
+        // Use twice the amount of required padding bytes for aligned_ptr below.
+        dav1d->pool = av_buffer_pool_init(ret + DAV1D_PICTURE_ALIGNMENT * 2, NULL);
+        if (!dav1d->pool)
+            return -ENOMEM;
+        dav1d->pool_size = ret;
+    }
+    buf = av_buffer_pool_get(dav1d->pool);
+    if (!buf)
+        return -ENOMEM;
+
+    // libdav1d requires DAV1D_PICTURE_ALIGNMENT aligned buffers, which av_malloc()
+    // doesn't guarantee for example when AVX is disabled at configure time.
+    // Use the extra DAV1D_PICTURE_ALIGNMENT padding bytes in the buffer to align it
+    // if required.
+    aligned_ptr = (uint8_t *)FFALIGN((uintptr_t)buf->data, DAV1D_PICTURE_ALIGNMENT);
+    ret = av_image_fill_pointers(data, format, h, aligned_ptr, linesize);
+    if (ret < 0) {
+        av_buffer_unref(&buf);
+        return ret;
+    }
+
+    p->data[0] = data[0];
+    p->data[1] = data[1];
+    p->data[2] = data[2];
+    p->stride[0] = linesize[0];
+    p->stride[1] = linesize[1];
+    p->allocator_data = buf;
+
+    return 0;
+}
+
+static void libdav1d_picture_release(Dav1dPicture *p, void *cookie) {
+    AVBufferRef *buf = p->allocator_data;
+
+    av_buffer_unref(&buf);
+}
+
 static av_cold int libdav1d_init(AVCodecContext *c)
 {
     Libdav1dContext *dav1d = c->priv_data;
@@ -55,6 +116,9 @@ static av_cold int libdav1d_init(AVCodecContext *c)
     dav1d_default_settings(&s);
     s.logger.cookie = c;
     s.logger.callback = libdav1d_log_callback;
+    s.allocator.cookie = dav1d;
+    s.allocator.alloc_picture_callback = libdav1d_picture_allocator;
+    s.allocator.release_picture_callback = libdav1d_picture_release;
     s.n_tile_threads = dav1d->tile_threads;
     s.apply_grain = dav1d->apply_grain;
     s.n_frame_threads = FFMIN(c->thread_count ? c->thread_count : av_cpu_count(), DAV1D_MAX_FRAME_THREADS);
@@ -87,13 +151,6 @@ static void libdav1d_frame_free(void *opaque, uint8_t *data) {
     av_free(p);
 }
 
-static const enum AVPixelFormat pix_fmt[][3] = {
-    [DAV1D_PIXEL_LAYOUT_I400] = { AV_PIX_FMT_GRAY8,   AV_PIX_FMT_GRAY10,    AV_PIX_FMT_GRAY12 },
-    [DAV1D_PIXEL_LAYOUT_I420] = { AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV420P10, AV_PIX_FMT_YUV420P12 },
-    [DAV1D_PIXEL_LAYOUT_I422] = { AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV422P12 },
-    [DAV1D_PIXEL_LAYOUT_I444] = { AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV444P10, AV_PIX_FMT_YUV444P12 },
-};
-
 static int libdav1d_receive_frame(AVCodecContext *c, AVFrame *frame)
 {
     Libdav1dContext *dav1d = c->priv_data;
@@ -222,6 +279,7 @@ static av_cold int libdav1d_close(AVCodecContext *c)
 {
     Libdav1dContext *dav1d = c->priv_data;
 
+    av_buffer_pool_uninit(&dav1d->pool);
     dav1d_data_unref(&dav1d->data);
     dav1d_close(&dav1d->c);
 
-- 
2.21.0