[FFmpeg-devel] [PATCH 13/14] mmal: add option copy_frame to support retrieving sw frames w/o copy

[wm4]

On Fri, 15 Dec 2017 15:05:50 +0800
wbsecg1 at gmail.com wrote:

> From: wang-bin <wbsecg1 at gmail.com>
> 
> mmal buffer->data is already in host memory. AFAIK decoders implemented in omx must
> be configured to output frames to either memory or something directly used by renderer,
> for example mediacodec surface, mmal buffer and omxil eglimage.
> test result: big buck bunny 1080p fps increases from about 100 to 110 if copy_frame is
> turned off
> ---
>  libavcodec/mmaldec.c | 31 +++++++++++++++++++++++--------
>  1 file changed, 23 insertions(+), 8 deletions(-)
> 
> diff --git a/libavcodec/mmaldec.c b/libavcodec/mmaldec.c
> index c1cfb09283..9cd6c6558f 100644
> --- a/libavcodec/mmaldec.c
> +++ b/libavcodec/mmaldec.c
> @@ -69,6 +69,7 @@ typedef struct MMALDecodeContext {
>      AVClass *av_class;
>      int extra_buffers;
>      int extra_decoder_buffers;
> +    int copy_frame;
>  
>      MMAL_COMPONENT_T *decoder;
>      MMAL_QUEUE_T *queue_decoded_frames;
> @@ -139,7 +140,6 @@ static int ffmmal_set_ref(AVFrame *frame, FFPoolRef *pool,
>      atomic_fetch_add_explicit(&ref->pool->refcount, 1, memory_order_relaxed);
>      mmal_buffer_header_acquire(buffer);
>  
> -    frame->format = AV_PIX_FMT_MMAL;
>      frame->data[3] = (uint8_t *)ref->buffer;
>      return 0;
>  }
> @@ -650,20 +650,34 @@ static int ffmal_copy_frame(AVCodecContext *avctx,  AVFrame *frame,
>  
>          if ((ret = ffmmal_set_ref(frame, ctx->pool_out, buffer)) < 0)
>              goto done;
> +        frame->format = AV_PIX_FMT_MMAL;
>      } else {
>          int w = FFALIGN(avctx->width, 32);
>          int h = FFALIGN(avctx->height, 16);
>          uint8_t *src[4];
>          int linesize[4];
>  
> -        if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
> -            goto done;
> +        if (ctx->copy_frame) {
> +            if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
> +                goto done;
>  
> -        av_image_fill_arrays(src, linesize,
> -                             buffer->data + buffer->type->video.offset[0],
> -                             avctx->pix_fmt, w, h, 1);
> -        av_image_copy(frame->data, frame->linesize, src, linesize,
> -                      avctx->pix_fmt, avctx->width, avctx->height);
> +            av_image_fill_arrays(src, linesize,
> +                                buffer->data + buffer->type->video.offset[0],
> +                                avctx->pix_fmt, w, h, 1);
> +            av_image_copy(frame->data, frame->linesize, src, linesize,
> +                        avctx->pix_fmt, avctx->width, avctx->height);
> +        } else {
> +            if ((ret = ff_decode_frame_props(avctx, frame)) < 0)
> +                goto done;
> +            /* buffer->type->video.offset/pitch[i]; is always 0 */
> +            av_image_fill_arrays(src, linesize,
> +                                buffer->data + buffer->type->video.offset[0],
> +                                avctx->pix_fmt, w, h, 1);
> +            if ((ret = ffmmal_set_ref(frame, ctx->pool_out, buffer)) < 0)
> +                goto done;
> +            memcpy(frame->data, src, sizeof(src));
> +            memcpy(frame->linesize, linesize, sizeof(linesize));
> +        }
>      }
>  
>      frame->pts = buffer->pts == MMAL_TIME_UNKNOWN ? AV_NOPTS_VALUE : buffer->pts;
> @@ -842,6 +856,7 @@ AVHWAccel ff_wmv3_mmal_hwaccel = {
>  static const AVOption options[]={
>      {"extra_buffers", "extra buffers", offsetof(MMALDecodeContext, extra_buffers), AV_OPT_TYPE_INT, {.i64 = 10}, 0, 256, 0},
>      {"extra_decoder_buffers", "extra MMAL internal buffered frames", offsetof(MMALDecodeContext, extra_decoder_buffers), AV_OPT_TYPE_INT, {.i64 = 10}, 0, 256, 0},
> +    {"copy_frame", "copy deocded data to avframe", offsetof(MMALDecodeContext, copy_frame), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 256, 0},
>      {NULL}
>  };
>  

Didn't check too closely what exactly the patch does, but adding an
option for it sounds very wrong. The user select in the get_format
callback whether a GPU surface is output (MMAL pixfmt), or software.