omx: Add support for zerocopy input of frames

This can only be used if the input data happens to be laid out
exactly correctly.

This might not be supported on all encoders, so only enable it
with an option, but enable it automatically on raspberry pi,
where it is known to be supported.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavcodec/omx.c

@@ -224,6 +224,8 @@ typedef struct OMXCodecContext {
 
     uint8_t *output_buf;
     int output_buf_size;
+
+    int input_zerocopy;
 } OMXCodecContext;
 
 static void append_buffer(pthread_mutex_t *mutex, pthread_cond_t *cond,
@@ -303,6 +305,15 @@ static OMX_ERRORTYPE empty_buffer_done(OMX_HANDLETYPE component, OMX_PTR app_dat
                                        OMX_BUFFERHEADERTYPE *buffer)
 {
     OMXCodecContext *s = app_data;
+    if (s->input_zerocopy) {
+        if (buffer->pAppPrivate) {
+            if (buffer->pOutputPortPrivate)
+                av_free(buffer->pAppPrivate);
+            else
+                av_frame_free((AVFrame**)&buffer->pAppPrivate);
+            buffer->pAppPrivate = NULL;
+        }
+    }
     append_buffer(&s->input_mutex, &s->input_cond,
                   &s->num_free_in_buffers, s->free_in_buffers, buffer);
     return OMX_ErrorNone;
@@ -525,8 +536,14 @@ static av_cold int omx_component_init(AVCodecContext *avctx, const char *role)
     s->done_out_buffers   = av_mallocz(sizeof(OMX_BUFFERHEADERTYPE*) * s->num_out_buffers);
     if (!s->in_buffer_headers || !s->free_in_buffers || !s->out_buffer_headers || !s->done_out_buffers)
         return AVERROR(ENOMEM);
-    for (i = 0; i < s->num_in_buffers && err == OMX_ErrorNone; i++)
+    for (i = 0; i < s->num_in_buffers && err == OMX_ErrorNone; i++) {
+        if (s->input_zerocopy)
+            err = OMX_UseBuffer(s->handle, &s->in_buffer_headers[i], s->in_port, s, in_port_params.nBufferSize, NULL);
+        else
             err = OMX_AllocateBuffer(s->handle, &s->in_buffer_headers[i],  s->in_port,  s, in_port_params.nBufferSize);
+        if (err == OMX_ErrorNone)
+            s->in_buffer_headers[i]->pAppPrivate = s->in_buffer_headers[i]->pOutputPortPrivate = NULL;
+    }
     CHECK(err);
     s->num_in_buffers = i;
     for (i = 0; i < s->num_out_buffers && err == OMX_ErrorNone; i++)
@@ -571,6 +588,8 @@ static av_cold void cleanup(OMXCodecContext *s)
         for (i = 0; i < s->num_in_buffers; i++) {
             OMX_BUFFERHEADERTYPE *buffer = get_buffer(&s->input_mutex, &s->input_cond,
                                                       &s->num_free_in_buffers, s->free_in_buffers, 1);
+            if (s->input_zerocopy)
+                buffer->pBuffer = NULL;
             OMX_FreeBuffer(s->handle, s->in_port, buffer);
         }
         for (i = 0; i < s->num_out_buffers; i++) {
@@ -611,6 +630,10 @@ static av_cold int omx_encode_init(AVCodecContext *avctx)
     OMX_BUFFERHEADERTYPE *buffer;
     OMX_ERRORTYPE err;
 
+#if CONFIG_OMX_RPI
+    s->input_zerocopy = 1;
+#endif
+
     s->omx_context = omx_init(avctx, s->libname, s->libprefix);
     if (!s->omx_context)
         return AVERROR_ENCODER_NOT_FOUND;
@@ -706,10 +729,56 @@ static int omx_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
     if (frame) {
         uint8_t *dst[4];
         int linesize[4];
+        int need_copy;
         buffer = get_buffer(&s->input_mutex, &s->input_cond,
                             &s->num_free_in_buffers, s->free_in_buffers, 1);
 
         buffer->nFilledLen = av_image_fill_arrays(dst, linesize, buffer->pBuffer, avctx->pix_fmt, s->stride, s->plane_size, 1);
+
+        if (s->input_zerocopy) {
+            uint8_t *src[4] = { NULL };
+            int src_linesize[4];
+            av_image_fill_arrays(src, src_linesize, frame->data[0], avctx->pix_fmt, s->stride, s->plane_size, 1);
+            if (frame->linesize[0] == src_linesize[0] &&
+                frame->linesize[1] == src_linesize[1] &&
+                frame->linesize[2] == src_linesize[2] &&
+                frame->data[1] == src[1] &&
+                frame->data[2] == src[2]) {
+                // If the input frame happens to have all planes stored contiguously,
+                // with the right strides, just clone the frame and set the OMX
+                // buffer header to point to it
+                AVFrame *local = av_frame_clone(frame);
+                if (!local) {
+                    // Return the buffer to the queue so it's not lost
+                    append_buffer(&s->input_mutex, &s->input_cond, &s->num_free_in_buffers, s->free_in_buffers, buffer);
+                    return AVERROR(ENOMEM);
+                } else {
+                    buffer->pAppPrivate = local;
+                    buffer->pOutputPortPrivate = NULL;
+                    buffer->pBuffer = local->data[0];
+                    need_copy = 0;
+                }
+            } else {
+                // If not, we need to allocate a new buffer with the right
+                // size and copy the input frame into it.
+                uint8_t *buf = av_malloc(av_image_get_buffer_size(avctx->pix_fmt, s->stride, s->plane_size, 1));
+                if (!buf) {
+                    // Return the buffer to the queue so it's not lost
+                    append_buffer(&s->input_mutex, &s->input_cond, &s->num_free_in_buffers, s->free_in_buffers, buffer);
+                    return AVERROR(ENOMEM);
+                } else {
+                    buffer->pAppPrivate = buf;
+                    // Mark that pAppPrivate is an av_malloc'ed buffer, not an AVFrame
+                    buffer->pOutputPortPrivate = (void*) 1;
+                    buffer->pBuffer = buf;
+                    need_copy = 1;
+                    buffer->nFilledLen = av_image_fill_arrays(dst, linesize, buffer->pBuffer, avctx->pix_fmt, s->stride, s->plane_size, 1);
+                }
+            }
+        } else {
+            need_copy = 1;
+        }
+        if (need_copy)
             av_image_copy(dst, linesize, (const uint8_t**) frame->data, frame->linesize, avctx->pix_fmt, avctx->width, avctx->height);
         buffer->nFlags = OMX_BUFFERFLAG_ENDOFFRAME;
         buffer->nOffset = 0;
@@ -808,9 +877,11 @@ static av_cold int omx_encode_end(AVCodecContext *avctx)
 
 #define OFFSET(x) offsetof(OMXCodecContext, x)
 #define VDE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_ENCODING_PARAM
+#define VE  AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {
     { "omx_libname", "OpenMAX library name", OFFSET(libname), AV_OPT_TYPE_STRING, { 0 }, 0, 0, VDE },
     { "omx_libprefix", "OpenMAX library prefix", OFFSET(libprefix), AV_OPT_TYPE_STRING, { 0 }, 0, 0, VDE },
+    { "zerocopy", "Try to avoid copying input frames if possible", OFFSET(input_zerocopy), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, VE },
     { NULL }
 };
 

libavcodec/version.h

@@ -29,7 +29,7 @@
 
 #define LIBAVCODEC_VERSION_MAJOR 57
 #define LIBAVCODEC_VERSION_MINOR 18
-#define LIBAVCODEC_VERSION_MICRO  1
+#define LIBAVCODEC_VERSION_MICRO  2
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \