tonylight2016

filter_video

Dec 1st, 2020
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  1. /*
  2.  * Copyright (c) 2010 Nicolas George
  3.  * Copyright (c) 2011 Stefano Sabatini
  4.  *
  5.  * Permission is hereby granted, free of charge, to any person obtaining a copy
  6.  * of this software and associated documentation files (the "Software"), to deal
  7.  * in the Software without restriction, including without limitation the rights
  8.  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  9.  * copies of the Software, and to permit persons to whom the Software is
  10.  * furnished to do so, subject to the following conditions:
  11.  *
  12.  * The above copyright notice and this permission notice shall be included in
  13.  * all copies or substantial portions of the Software.
  14.  *
  15.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17.  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  18.  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19.  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20.  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21.  * THE SOFTWARE.
  22.  */
  23.  
  24. /**
  25.  * @file
  26.  * API example for decoding and filtering
  27.  * @example filtering_video.c
  28.  */
  29.  
  30. #define _XOPEN_SOURCE 600 /* for usleep */
  31. #include <unistd.h>
  32.  
  33. #include <libavcodec/avcodec.h>
  34. #include <libavformat/avformat.h>
  35. #include <libavfilter/avfiltergraph.h>
  36. #include <libavfilter/avcodec.h>
  37. #include <libavfilter/buffersink.h>
  38. #include <libavfilter/buffersrc.h>
  39. #include <libavutil/opt.h>
  40.  
  41. const char *filter_descr = "scale=78:24";
  42.  
  43. static AVFormatContext *fmt_ctx;
  44. static AVCodecContext *dec_ctx;
  45. AVFilterContext *buffersink_ctx;
  46. AVFilterContext *buffersrc_ctx;
  47. AVFilterGraph *filter_graph;
  48. static int video_stream_index = -1;
  49. static int64_t last_pts = AV_NOPTS_VALUE;
  50.  
  51. static int open_input_file(const char *filename)
  52. {
  53.     int ret;
  54.     AVCodec *dec;
  55.  
  56.     if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
  57.         av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
  58.         return ret;
  59.     }
  60.  
  61.     if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
  62.         av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
  63.         return ret;
  64.     }
  65.  
  66.     /* select the video stream */
  67.     ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
  68.     if (ret < 0) {
  69.         av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
  70.         return ret;
  71.     }
  72.     video_stream_index = ret;
  73.     dec_ctx = fmt_ctx->streams[video_stream_index]->codec;
  74.     av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
  75.  
  76.     /* init the video decoder */
  77.     if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
  78.         av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
  79.         return ret;
  80.     }
  81.  
  82.     return 0;
  83. }
  84.  
  85. static int init_filters(const char *filters_descr)
  86. {
  87.     char args[512];
  88.     int ret = 0;
  89.     AVFilter *buffersrc  = avfilter_get_by_name("buffer");
  90.     AVFilter *buffersink = avfilter_get_by_name("buffersink");
  91.     AVFilterInOut *outputs = avfilter_inout_alloc();
  92.     AVFilterInOut *inputs  = avfilter_inout_alloc();
  93.     AVRational time_base = fmt_ctx->streams[video_stream_index]->time_base;
  94.     enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
  95.  
  96.     filter_graph = avfilter_graph_alloc();
  97.     if (!outputs || !inputs || !filter_graph) {
  98.         ret = AVERROR(ENOMEM);
  99.         goto end;
  100.     }
  101.  
  102.     /* buffer video source: the decoded frames from the decoder will be inserted here. */
  103.     snprintf(args, sizeof(args),
  104.             "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  105.             dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
  106.             time_base.num, time_base.den,
  107.             dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
  108.  
  109.     ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
  110.                                        args, NULL, filter_graph);
  111.     if (ret < 0) {
  112.         av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
  113.         goto end;
  114.     }
  115.  
  116.     /* buffer video sink: to terminate the filter chain. */
  117.     ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
  118.                                        NULL, NULL, filter_graph);
  119.     if (ret < 0) {
  120.         av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
  121.         goto end;
  122.     }
  123.  
  124.     ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
  125.                               AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN);
  126.     if (ret < 0) {
  127.         av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
  128.         goto end;
  129.     }
  130.  
  131.     /*
  132.      * Set the endpoints for the filter graph. The filter_graph will
  133.      * be linked to the graph described by filters_descr.
  134.      */
  135.  
  136.     /*
  137.      * The buffer source output must be connected to the input pad of
  138.      * the first filter described by filters_descr; since the first
  139.      * filter input label is not specified, it is set to "in" by
  140.      * default.
  141.      */
  142.     outputs->name       = av_strdup("in");
  143.     outputs->filter_ctx = buffersrc_ctx;
  144.     outputs->pad_idx    = 0;
  145.     outputs->next       = NULL;
  146.  
  147.     /*
  148.      * The buffer sink input must be connected to the output pad of
  149.      * the last filter described by filters_descr; since the last
  150.      * filter output label is not specified, it is set to "out" by
  151.      * default.
  152.      */
  153.     inputs->name       = av_strdup("out");
  154.     inputs->filter_ctx = buffersink_ctx;
  155.     inputs->pad_idx    = 0;
  156.     inputs->next       = NULL;
  157.  
  158.     if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
  159.                                     &inputs, &outputs, NULL)) < 0)
  160.         goto end;
  161.  
  162.     if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
  163.         goto end;
  164.  
  165. end:
  166.     avfilter_inout_free(&inputs);
  167.     avfilter_inout_free(&outputs);
  168.  
  169.     return ret;
  170. }
  171.  
  172. static void display_frame(const AVFrame *frame, AVRational time_base)
  173. {
  174.     int x, y;
  175.     uint8_t *p0, *p;
  176.     int64_t delay;
  177.  
  178.     if (frame->pts != AV_NOPTS_VALUE) {
  179.         if (last_pts != AV_NOPTS_VALUE) {
  180.             /* sleep roughly the right amount of time;
  181.              * usleep is in microseconds, just like AV_TIME_BASE. */
  182.             delay = av_rescale_q(frame->pts - last_pts,
  183.                                  time_base, AV_TIME_BASE_Q);
  184.             if (delay > 0 && delay < 1000000)
  185.                 usleep(delay);
  186.         }
  187.         last_pts = frame->pts;
  188.     }
  189.  
  190.     /* Trivial ASCII grayscale display. */
  191.     p0 = frame->data[0];
  192.     puts("\033c");
  193.     for (y = 0; y < frame->height; y++) {
  194.         p = p0;
  195.         for (x = 0; x < frame->width; x++)
  196.             putchar(" .-+#"[*(p++) / 52]);
  197.         putchar('\n');
  198.         p0 += frame->linesize[0];
  199.     }
  200.     fflush(stdout);
  201. }
  202.  
  203. int main(int argc, char **argv)
  204. {
  205.     int ret;
  206.     AVPacket packet;
  207.     AVFrame *frame = av_frame_alloc();
  208.     AVFrame *filt_frame = av_frame_alloc();
  209.     int got_frame;
  210.  
  211.     if (!frame || !filt_frame) {
  212.         perror("Could not allocate frame");
  213.         exit(1);
  214.     }
  215.     if (argc != 2) {
  216.         fprintf(stderr, "Usage: %s file\n", argv[0]);
  217.         exit(1);
  218.     }
  219.  
  220.     av_register_all();
  221.     avfilter_register_all();
  222.  
  223.     if ((ret = open_input_file(argv[1])) < 0)
  224.         goto end;
  225.     if ((ret = init_filters(filter_descr)) < 0)
  226.         goto end;
  227.  
  228.     /* read all packets */
  229.     while (1) {
  230.         if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
  231.             break;
  232.  
  233.         if (packet.stream_index == video_stream_index) {
  234.             got_frame = 0;
  235.             ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
  236.             if (ret < 0) {
  237.                 av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
  238.                 break;
  239.             }
  240.  
  241.             if (got_frame) {
  242.                 frame->pts = av_frame_get_best_effort_timestamp(frame);
  243.  
  244.                 /* push the decoded frame into the filtergraph */
  245.                 if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
  246.                     av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
  247.                     break;
  248.                 }
  249.  
  250.                 /* pull filtered frames from the filtergraph */
  251.                 while (1) {
  252.                     ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
  253.                     if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
  254.                         break;
  255.                     if (ret < 0)
  256.                         goto end;
  257.                     display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
  258.                     av_frame_unref(filt_frame);
  259.                 }
  260.                 av_frame_unref(frame);
  261.             }
  262.         }
  263.         av_free_packet(&packet);
  264.     }
  265. end:
  266.     avfilter_graph_free(&filter_graph);
  267.     avcodec_close(dec_ctx);
  268.     avformat_close_input(&fmt_ctx);
  269.     av_frame_free(&frame);
  270.     av_frame_free(&filt_frame);
  271.  
  272.     if (ret < 0 && ret != AVERROR_EOF) {
  273.         fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
  274.         exit(1);
  275.     }
  276.  
  277.     exit(0);
  278. }
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