Shulou(Shulou.com)06/03 Report--

Header file

Extern "C" {

# include "libavutil/mem.h"

# include "libavfilter/avfiltergraph.h"

# include "libavfilter/buffersink.h"

# include "libavfilter/buffersrc.h"

# include "libavutil/avutil.h"

# include "libavutil/imgutils.h"

# include "libavdevice/avdevice.h"

}

Registration filter

Avfilter_register_all ()

/ *

For pSrcFrame frame, the final image data is saved in pDestFrame

, /

Void VideoDecodec::DrawRectangleToFrame (AVFrame* pSrcFrame, AVFrame* pDestFrame, int x, int y, int w, int h)

{

AVFilterGraph* pFilterGraph = avfilter_graph_alloc ()

Char szErrMsg [128] = {0}

Char szArgs [512] = {0}

Char szFilterDescr [256] = {0}

Sprintf (szFilterDescr, "drawbox=x=%d:y=%d:w=%d:h=%d:color=yellow@1", x, y, w, h)

AVFilter* pBufferSrc = avfilter_get_by_name ("buffer")

AVFilter* pBufferSink = avfilter_get_by_name ("buffersink")

AVFilterInOut* pFilterOut = avfilter_inout_alloc ()

AVFilterInOut* pFilterIn = avfilter_inout_alloc ()

Enum AVPixelFormat pix_fmts [] = {AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_NONE}

AVBufferSinkParams* pBufferSinkParams

/ / the last few parameters do not use real video format parameters

Snprintf (szArgs, sizeof (szArgs), "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d"

PSrcFrame- > width, pSrcFrame- > height, pSrcFrame- > format, 1,1,1,1)

Int ret = 0

AVFilterContext* pBufferSinkContext = NULL

AVFilterContext* pBufferSrcContext = NULL

If ((ret = avfilter_graph_create_filter (& pBufferSrcContext, pBufferSrc, "in", szArgs, NULL, pFilterGraph))

< 0) { sprintf(szErrMsg, "Cannot graph create filter, error:%s\n", av_err2str(ret)); return; } pBufferSinkParams = av_buffersink_params_alloc(); pBufferSinkParams->

Pixel_fmts = pix_fmts

If ((ret = avfilter_graph_create_filter (& pBufferSinkContext, pBufferSink, "out", NULL, pBufferSinkParams, pFilterGraph))

< 0) { sprintf(szErrMsg, "Cannot graph create filter, error:%s\n", av_err2str(ret)); return; } pFilterOut->

Name = av_strdup ("in")

PFilterOut- > filter_ctx = pBufferSrcContext

PFilterOut- > pad_idx = 0

PFilterOut- > next = NULL

PFilterIn- > name = av_strdup ("out")

PFilterIn- > filter_ctx = pBufferSinkContext

PFilterIn- > pad_idx = 0

PFilterIn- > next = NULL

Do

{

If ((ret = avfilter_graph_parse_ptr (pFilterGraph, szFilterDescr, & pFilterIn, & pFilterOut, NULL) < 0)

{

Sprintf (szErrMsg, "Cannot graph parse ptr, error:%s\ n", av_err2str (ret))

Break

}

If ((ret = avfilter_graph_config (pFilterGraph, NULL)) < 0)

{

Sprintf (szErrMsg, "Cannot graph config filter, error:%s\ n", av_err2str (ret))

Break

}

If ((ret = av_buffersrc_add_frame (pBufferSrcContext, pSrcFrame)) < 0)

{

Sprintf (szErrMsg, "Cannot add frame from buffersrc, error:%s\ n", av_err2str (ret))

Break

}

/ / the length and width of pDestFrame frames must be specified.

/ / after the image format conversion, the data data in pSrcFrame is set to NULL,pSrcFrame structure is not available

If ((ret = av_buffersink_get_frame (pBufferSinkContext, pDestFrame)) < 0)

{

Sprintf (szErrMsg, "Cannot get frame frome buffersink, error:%s\ n", av_err2str (ret))

Break

}

} while (0)

Avfilter_inout_free & pFilterIn)

Avfilter_inout_free & pFilterOut)

Av_free (pBufferSinkParams)

Avfilter_graph_free & pFilterGraph)

}

Be careful

1. When calling avfilter_get_by_name ("ffbuffersink"), the ffmpeg in the new version 3.4 should be changed to avfilter_get_by_name ("buffersink"); otherwise, the return pointer is empty, and the call avfilter_graph_create_filter returns-12.

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