[FFmpeg-user] Fwd: Adding a text on top of video using libavfilter API.
prajwal kulkarni
prajwalrk123 at gmail.com
Mon Feb 18 12:52:55 CET 2013
Hi all,
I am trying to add a visible text ‘sampletext’ on a video and store in
another file called “myvideo.mp4”
Below is my code.(developed from *doc/examples/filtering_video.c *example).
* *
*#define _XOPEN_SOURCE 600 /* for usleep */*
*#include <unistd.h>*
* *
*#include <libavcodec/avcodec.h>*
*#include <libavformat/avformat.h>*
*#include <libavfilter/avfiltergraph.h>*
*#include <libavfilter/avcodec.h>*
*#include <libavfilter/buffersink.h>*
*#include <libavfilter/buffersrc.h>*
* *
*const char *filter_descr =
"drawtext=fontcolor=white:fontfile=/usr/share/fonts/liberation/LiberationMono-Bold.ttf:text='samleptext'";
*
* *
*static AVFormatContext *fmt_ctx;*
*static AVCodecContext *dec_ctx;*
*AVFilterContext *buffersink_ctx;*
*AVFilterContext *buffersrc_ctx;*
*AVFilterGraph *filter_graph;*
*static int video_stream_index = -1;*
*static int64_t last_pts = AV_NOPTS_VALUE;*
* *
*static int open_input_file(const char *filename)*
*{*
* int ret;*
* AVCodec *dec;*
* *
* if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {*
* av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");*
* return ret;*
* }*
* *
* if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {*
* av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");*
* return ret;*
* }*
* *
* /* select the video stream */*
* ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec,
0);*
* if (ret < 0) {*
* av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the
input file\n");*
* return ret;*
* }*
* video_stream_index = ret;*
* dec_ctx = fmt_ctx->streams[video_stream_index]->codec;*
* *
* /* init the video decoder */*
* if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {*
* av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");*
* return ret;*
* }*
* *
* return 0;*
*}*
* *
*static int init_filters(const char *filters_descr)*
*{*
* char args[512];*
* int ret;*
* AVFilter *buffersrc = avfilter_get_by_name("buffer");*
* AVFilter *buffersink = avfilter_get_by_name("ffbuffersink");*
* AVFilterInOut *outputs = avfilter_inout_alloc();*
* AVFilterInOut *inputs = avfilter_inout_alloc();*
* enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };*
* AVBufferSinkParams *buffersink_params;*
* *
* filter_graph = avfilter_graph_alloc();*
* *
* /* buffer video source: the decoded frames from the decoder will be
inserted here. */*
* snprintf(args, sizeof(args),*
*
"video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",*
* dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,*
* dec_ctx->time_base.num, dec_ctx->time_base.den,*
* dec_ctx->sample_aspect_ratio.num,
dec_ctx->sample_aspect_ratio.den);*
* *
* ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",*
* args, NULL, filter_graph);*
* if (ret < 0) {*
* av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");*
* return ret;*
* }*
* *
* /* buffer video sink: to terminate the filter chain. */*
* buffersink_params = av_buffersink_params_alloc();*
* buffersink_params->pixel_fmts = pix_fmts;*
* ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",*
* NULL, buffersink_params,
filter_graph);*
* av_free(buffersink_params);*
* if (ret < 0) {*
* av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");*
* return ret;*
* }*
* *
* /* Endpoints for the filter graph. */*
* outputs->name = av_strdup("in");*
* outputs->filter_ctx = buffersrc_ctx;*
* outputs->pad_idx = 0;*
* outputs->next = NULL;*
* *
* inputs->name = av_strdup("out");*
* inputs->filter_ctx = buffersink_ctx;*
* inputs->pad_idx = 0;*
* inputs->next = NULL;*
* *
* if ((ret = avfilter_graph_parse(filter_graph, filters_descr,*
* &inputs, &outputs, NULL)) < 0)*
* return ret;*
* *
* if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)*
* return ret;*
* return 0;*
*}*
* *
*static void save_picref(AVFilterBufferRef *picref, AVRational time_base)*
*{*
* int x, y;*
* uint8_t *p0, *p;*
* int64_t delay;*
* FILE *pFile;*
* char szFilename[32]="myvideo.mp4";*
* *
* // Open file*
* pFile=fopen(szFilename, "wb");*
* if(pFile==NULL)*
* return;*
* *
* if (picref->pts != AV_NOPTS_VALUE) {*
* if (last_pts != AV_NOPTS_VALUE) {*
* /* sleep roughly the right amount of time;*
* * usleep is in microseconds, just like AV_TIME_BASE. */*
* delay = av_rescale_q(picref->pts - last_pts,*
* time_base, AV_TIME_BASE_Q);*
* if (delay > 0 && delay < 1000000)*
* usleep(delay);*
* }*
* last_pts = picref->pts;*
* }*
* fprintf(pFile, "P6\n%d %d\n255\n", picref->video->w, picref->video->h);*
* // Write pixel data*
* for(y=0; y<picref->video->w; y++)*
* fwrite(picref->data[0], 1, picref->video->w*3, pFile);*
* *
* // Close file*
* fclose(pFile);*
* *
*}*
* *
*int main(int argc, char **argv)*
*{*
* int ret;*
* AVPacket packet;*
* AVFrame frame;*
* int got_frame;*
* *
* if (argc != 2) {*
* fprintf(stderr, "Usage: %s file\n", argv[0]);*
* exit(1);*
* }*
* *
* avcodec_register_all();*
* av_register_all();*
* avfilter_register_all();*
* *
* if ((ret = open_input_file(argv[1])) < 0)*
* goto end;*
* if ((ret = init_filters(filter_descr)) < 0)*
* goto end;*
* *
* /* read all packets */*
* while (1) {*
* AVFilterBufferRef *picref;*
* if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)*
* break;*
* *
* if (packet.stream_index == video_stream_index) {*
* avcodec_get_frame_defaults(&frame);*
* got_frame = 0;*
* ret = avcodec_decode_video2(dec_ctx, &frame, &got_frame,
&packet);*
* if (ret < 0) {*
* av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");*
* break;*
* }*
* *
* if (got_frame) {*
* frame.pts = av_frame_get_best_effort_timestamp(&frame);*
* *
* /* push the decoded frame into the filtergraph */*
* if (av_buffersrc_add_frame(buffersrc_ctx, &frame, 0) < 0) {
*
* av_log(NULL, AV_LOG_ERROR, "Error while feeding the
filtergraph\n");*
* break;*
* }*
* *
* /* pull filtered pictures from the filtergraph */*
* while (1) {*
* ret = av_buffersink_get_buffer_ref(buffersink_ctx,
&picref, 0);*
* if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)*
* break;*
* if (ret < 0)*
* goto end;*
* *
* if (picref) {*
* save_picref(picref,
buffersink_ctx->inputs[0]->time_base);*
* avfilter_unref_bufferp(&picref);*
* }*
* }*
* }*
* }*
* av_free_packet(&packet);*
* }*
*end:*
* avfilter_graph_free(&filter_graph);*
* if (dec_ctx)*
* avcodec_close(dec_ctx);*
* avformat_close_input(&fmt_ctx);*
* *
* if (ret < 0 && ret != AVERROR_EOF) {*
* char buf[1024];*
* av_strerror(ret, buf, sizeof(buf));*
* fprintf(stderr, "Error occurred: %s\n", buf);*
* exit(1);*
* }*
* *
* exit(0);*
*}*
* *
After compilation and execution, when I try to play the video using
*ffplay myvideo.mp4 *
I am getting the following error.
*myvideo.mp4: Invalid data found when processing input*
* *
i am unable to resolve the error,can anyone pls help me out in solving the
error.
* *
* *
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