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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 doc/examples/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.  
  40. const char *filter_descr = "scale=78:24";
  41.  
  42. static AVFormatContext *fmt_ctx;
  43. static AVCodecContext *dec_ctx;
  44. AVFilterContext *buffersink_ctx;
  45. AVFilterContext *buffersrc_ctx;
  46. AVFilterGraph *filter_graph;
  47. static int video_stream_index = -1;
  48. static int64_t last_pts = AV_NOPTS_VALUE;
  49.  
  50. static int open_input_file(const char *filename)
  51. {
  52.     int ret;
  53.     AVCodec *dec;
  54.  
  55.     if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
  56.         av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
  57.         return ret;
  58.     }
  59.  
  60.     if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
  61.         av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
  62.         return ret;
  63.     }
  64.  
  65.     /* select the video stream */
  66.     ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
  67.     if (ret < 0) {
  68.         av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
  69.         return ret;
  70.     }
  71.     video_stream_index = ret;
  72.     dec_ctx = fmt_ctx->streams[video_stream_index]->codec;
  73.  
  74.     /* init the video decoder */
  75.     if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
  76.         av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
  77.         return ret;
  78.     }
  79.  
  80.     return 0;
  81. }
  82.  
  83. static int init_filters(const char *filters_descr)
  84. {
  85.     char args[512];
  86.     int ret;
  87.     AVFilter *buffersrc  = avfilter_get_by_name("buffer");
  88.     AVFilter *buffersink = avfilter_get_by_name("buffersink");
  89.     AVFilterInOut *outputs = avfilter_inout_alloc();
  90.     AVFilterInOut *inputs  = avfilter_inout_alloc();
  91.     enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
  92.     AVBufferSinkParams *buffersink_params;
  93.  
  94.     filter_graph = avfilter_graph_alloc();
  95.  
  96.     /* buffer video source: the decoded frames from the decoder will be inserted here. */
  97.     snprintf(args, sizeof(args),
  98.             "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  99.             dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
  100.             dec_ctx->time_base.num, dec_ctx->time_base.den,
  101.             dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
  102.  
  103.     ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
  104.                                        args, NULL, filter_graph);
  105.     if (ret < 0) {
  106.         av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
  107.         return ret;
  108.     }
  109.  
  110.     /* buffer video sink: to terminate the filter chain. */
  111.     buffersink_params = av_buffersink_params_alloc();
  112.     buffersink_params->pixel_fmts = pix_fmts;
  113.     ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
  114.                                        NULL, buffersink_params, filter_graph);
  115.     av_free(buffersink_params);
  116.     if (ret < 0) {
  117.         av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
  118.         return ret;
  119.     }
  120.  
  121.     /* Endpoints for the filter graph. */
  122.     outputs->name       = av_strdup("in");
  123.     outputs->filter_ctx = buffersrc_ctx;
  124.     outputs->pad_idx    = 0;
  125.     outputs->next       = NULL;
  126.  
  127.     inputs->name       = av_strdup("out");
  128.     inputs->filter_ctx = buffersink_ctx;
  129.     inputs->pad_idx    = 0;
  130.     inputs->next       = NULL;
  131.  
  132.     if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
  133.                                     &inputs, &outputs, NULL)) < 0)
  134.         return ret;
  135.  
  136.     if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
  137.         return ret;
  138.     return 0;
  139. }
  140.  
  141. static void display_frame(const AVFrame *frame, AVRational time_base)
  142. {
  143.     int x, y;
  144.     uint8_t *p0, *p;
  145.     int64_t delay;
  146.  
  147.     if (frame->pts != AV_NOPTS_VALUE) {
  148.         if (last_pts != AV_NOPTS_VALUE) {
  149.             /* sleep roughly the right amount of time;
  150.              * usleep is in microseconds, just like AV_TIME_BASE. */
  151.             delay = av_rescale_q(frame->pts - last_pts,
  152.                                  time_base, AV_TIME_BASE_Q);
  153.             if (delay > 0 && delay < 1000000)
  154.                 usleep(delay);
  155.         }
  156.         last_pts = frame->pts;
  157.     }
  158.  
  159.     /* Trivial ASCII grayscale display. */
  160.     p0 = frame->data[0];
  161.     puts("\033c");
  162.     for (y = 0; y < frame->height; y++) {
  163.         p = p0;
  164.         for (x = 0; x < frame->width; x++)
  165.             putchar(" .-+#"[*(p++) / 52]);
  166.         putchar('\n');
  167.         p0 += frame->linesize[0];
  168.     }
  169.     fflush(stdout);
  170. }
  171.  
  172. int main(int argc, char **argv)
  173. {
  174.     int ret;
  175.     AVPacket packet;
  176.     AVFrame *frame = av_frame_alloc();
  177.     AVFrame *filt_frame = av_frame_alloc();
  178.     int got_frame;
  179.  
  180.     if (!frame || !filt_frame) {
  181.         perror("Could not allocate frame");
  182.         exit(1);
  183.     }
  184.     if (argc != 2) {
  185.         fprintf(stderr, "Usage: %s file\n", argv[0]);
  186.         exit(1);
  187.     }
  188.  
  189.     avcodec_register_all();
  190.     av_register_all();
  191.     avfilter_register_all();
  192.  
  193.     if ((ret = open_input_file(argv[1])) < 0)
  194.         goto end;
  195.     if ((ret = init_filters(filter_descr)) < 0)
  196.         goto end;
  197.  
  198.     /* read all packets */
  199.     while (1) {
  200.         if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
  201.             break;
  202.  
  203.         if (packet.stream_index == video_stream_index) {
  204.             avcodec_get_frame_defaults(frame);
  205.             got_frame = 0;
  206.             ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
  207.             if (ret < 0) {
  208.                 av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
  209.                 break;
  210.             }
  211.  
  212.             if (got_frame) {
  213.                 frame->pts = av_frame_get_best_effort_timestamp(frame);
  214.  
  215.                 /* push the decoded frame into the filtergraph */
  216.                 if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
  217.                     av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
  218.                     break;
  219.                 }
  220.  
  221.                 /* pull filtered frames from the filtergraph */
  222.                 while (1) {
  223.                     ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
  224.                     if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
  225.                         break;
  226.                     if (ret < 0)
  227.                         goto end;
  228.                     display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
  229.                     av_frame_unref(filt_frame);
  230.                 }
  231.             }
  232.         }
  233.         av_free_packet(&packet);
  234.     }
  235. end:
  236.     avfilter_graph_free(&filter_graph);
  237.     if (dec_ctx)
  238.         avcodec_close(dec_ctx);
  239.     avformat_close_input(&fmt_ctx);
  240.     av_frame_free(&frame);
  241.     av_frame_free(&filt_frame);
  242.  
  243.     if (ret < 0 && ret != AVERROR_EOF) {
  244.         char buf[1024];
  245.         av_strerror(ret, buf, sizeof(buf));
  246.         fprintf(stderr, "Error occurred: %s\n", buf);
  247.         exit(1);
  248.     }
  249.  
  250.     exit(0);
  251. }
  252.