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• Animated line chart with pandas, matplotlib and ffmpeg

  10 avril 2020, par Mark K

  In producing an animated line chart, I have below data and codes.

  



  But when the chart produced, it shows no line. What did I do wrong ?

  



  Thank you.

  



  import numpy as np
import pandas as pd
import seaborn as sns
import matplotlib
import matplotlib.pyplot as plt
import matplotlib.animation as animation

title = 'Heroin Overdoses'

data = {'Year' : ["1999","2000","2001","2002","2003","2004","2005","2006","2007","2008","2009","2010","2011","2012","2013","2014","2015","2016"], 
'Heroin Overdoses' : [280,443,413,486,475,148,197,170,448,103,137,160,483,356,352,300,466,278]}
overdose = pd.DataFrame(data)

Writer = animation.writers['ffmpeg']
writer = Writer(fps=20, metadata=dict(artist='Me'), bitrate=1800)

fig = plt.figure(figsize=(10,6))
plt.xlim(1999, 2016)
plt.ylim(np.min(overdose)[0], np.max(overdose)[0])
plt.xlabel('Year',fontsize=20)
plt.ylabel(title,fontsize=20)
plt.title('Heroin Overdoses per Year',fontsize=20)

def animate(i):
    data = overdose.iloc[:int(i+1)] #select data range
    p = sns.lineplot(x=data.index, y=data[title], data=data, color="r")
    p.tick_params(labelsize=17)
    plt.setp(p.lines,linewidth=7)

ani = matplotlib.animation.FuncAnimation(fig, animate, frames=17, repeat=True)

ani.save('C:\\folder\\line chart.mp4', writer=writer)


  


• ffmpeg DASH encoding : always getting bitrate as 200k for vp9 codec

  29 novembre 2019, par Saurabh

  I am using following command, earlier put here : to generate DASH files :

  ffmpeg -y -nostdin -loglevel error -i "$1" \
  
          -map 0:v:0  -map 0:v:0 -map 0:v:0  -map 0:v:0  -map 0:v:0  -map 0:v:0 -map 0:a\?:0  \
  
          -maxrate:v:0 350k -bufsize:v:0 700k -c:v:0 libx264 -filter:v:0 "scale=320:-2"  \
  
          -maxrate:v:1 1000k -bufsize:v:1 2000k -c:v:1 libx264 -filter:v:1 "scale=640:-2"  \
  
          -maxrate:v:2 3000k -bufsize:v:2 6000k -c:v:2 libx264 -filter:v:2 "scale=1280:-2" \
  
          -maxrate:v:3 300k -minrate:v:3 100k -bufsize:v:3 600k -c:v:3 libvpx-vp9 -filter:v:3 "scale=320:-2"  \
  
          -maxrate:v:4 1088k -minrate:v:4 200k -bufsize:v:4 2176k -c:v:4 libvpx-vp9 -filter:v:4 "scale=640:-2"  \
  
          -maxrate:v:5 1500k -minrate:v:5 300k -bufsize:v:5 3000k -c:v:5 libvpx-vp9 -filter:v:5 "scale=1280:-2"  \
  
          -use_timeline 1  -use_template 1 -adaptation_sets "id=0,streams=0,1,2 id=1,streams=3,4,5 id=2,streams=a" \
  
          -threads 8 -crf 3 -seg_duration 5 -hls_init_time 1 -hls_time 5 -hls_playlist true -f dash "$2"

  The issue is, in the output, I always get bandwidth as 200k for vp9 codec(see output below), while for same video bandwidth for h264 codec varies as par resolution and quite less, I expected vp9 to be even less as it compresses more. I have tested using multiple different options like : -b:v, -deadline, -cpu-used -crf, etc, but not working expected with different values of these, What am I missing ?

  Sample output mpd file :

  <?xml version="1.0" encoding="utf-8"?>
  
  <mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static" mediapresentationduration="PT25.4S" minbuffertime="PT15.0S">
  
      <programinformation>
  
      </programinformation>
  
      <period start="PT0.0S">
  
          <adaptationset contenttype="video" segmentalignment="true" bitstreamswitching="true" lang="und">
  
              <representation mimetype="video/mp4" codecs="avc1.64000c" bandwidth="104972" width="320" height="180" framerate="24000/1001">
  
                  <segmenttemplate timescale="24000" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
  
                      <segmenttimeline>
  
                          <s t="0" d="130130"></s>
  
                          <s d="250250"></s>
  
                          <s d="176176"></s>
  
                          <s d="54054"></s>
  
                      </segmenttimeline>
  
                  </segmenttemplate>
  
              </representation>
  
              <representation mimetype="video/mp4" codecs="avc1.64001e" bandwidth="227233" width="640" height="360" framerate="24000/1001">
  
                  <segmenttemplate timescale="24000" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
  
                      <segmenttimeline>
  
                          <s t="0" d="130130"></s>
  
                          <s d="250250"></s>
  
                          <s d="180180"></s>
  
                          <s d="50050"></s>
  
                      </segmenttimeline>
  
                  </segmenttemplate>
  
              </representation>
  
              <representation mimetype="video/mp4" codecs="avc1.64001f" bandwidth="616878" width="1280" height="720" framerate="24000/1001">
  
                  <segmenttemplate timescale="24000" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
  
                      <segmenttimeline>
  
                          <s t="0" d="130130"></s>
  
                          <s d="250250"></s>
  
                          <s d="180180"></s>
  
                          <s d="50050"></s>
  
                      </segmenttimeline>
  
                  </segmenttemplate>
  
              </representation>
  
          </adaptationset>
  
          <adaptationset contenttype="video" segmentalignment="true" bitstreamswitching="true" lang="und">
  
              <representation mimetype="video/mp4" codecs="vp09.00.11.08" bandwidth="200000" width="320" height="180" framerate="24000/1001">
  
                  <segmenttemplate timescale="24000" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
  
                      <segmenttimeline>
  
                          <s t="0" d="128128" r="3"></s>
  
                          <s d="98098"></s>
  
                      </segmenttimeline>
  
                  </segmenttemplate>
  
              </representation>
  
              <representation mimetype="video/mp4" codecs="vp09.00.21.08" bandwidth="200000" width="640" height="360" framerate="24000/1001">
  
                  <segmenttemplate timescale="24000" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
  
                      <segmenttimeline>
  
                          <s t="0" d="128128" r="3"></s>
  
                          <s d="98098"></s>
  
                      </segmenttimeline>
  
                  </segmenttemplate>
  
              </representation>
  
              <representation mimetype="video/mp4" codecs="vp09.00.31.08" bandwidth="200000" width="1280" height="720" framerate="24000/1001">
  
                  <segmenttemplate timescale="24000" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
  
                      <segmenttimeline>
  
                          <s t="0" d="128128" r="3"></s>
  
                          <s d="98098"></s>
  
                      </segmenttimeline>
  
                  </segmenttemplate>
  
              </representation>
  
          </adaptationset>
  
          <adaptationset contenttype="audio" segmentalignment="true" bitstreamswitching="true" lang="eng">
  
              <representation mimetype="audio/mp4" codecs="mp4a.40.2" bandwidth="128000" audiosamplingrate="44100">
  
                  <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>
  
                  <segmenttemplate timescale="44100" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
  
                      <segmenttimeline>
  
                          <s t="0" d="235520" r="3"></s>
  
                          <s d="180224"></s>
  
                      </segmenttimeline>
  
                  </segmenttemplate>
  
              </representation>
  
          </adaptationset>
  
      </period>
  
  </mpd>

  I am using this video, but it is coming same for all 30 sec video I have tried.

• avcodec_find_encoder_by_name() returns NULL

  27 décembre 2019, par GiuTor

  I’m trying to compile the following example I found on ffmpeg documentation :

   /*
  
   * Copyright (c) 2001 Fabrice Bellard
  
   *
  
   * Permission is hereby granted, free of charge, to any person obtaining a copy
  
   * of this software and associated documentation files (the "Software"), to deal
  
   * in the Software without restriction, including without limitation the rights
  
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  
   * copies of the Software, and to permit persons to whom the Software is
  
   * furnished to do so, subject to the following conditions:
  
   *
  
   * The above copyright notice and this permission notice shall be included in
  
   * all copies or substantial portions of the Software.
  
   *
  
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  
   * THE SOFTWARE.
  
   */
  
  
  
   // compile with gcc -o encode_video encode_video.c -lavutil -lavcodec -lz -lm
  
  
  
  /**
  
   * @file
  
   * video encoding with libavcodec API example
  
   *
  
   * @example encode_video.c
  
   */
  
  
  
  #include 
  
  #include 
  
  #include 
  
  
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  
  
  #include <libavutil></libavutil>opt.h>
  
  #include <libavutil></libavutil>imgutils.h>
  
  
  
  static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
  
                     FILE *outfile)
  
  {
  
      int ret;
  
  
  
      /* send the frame to the encoder */
  
      if (frame)
  
          printf("Send frame %3"PRId64"\n", frame->pts);
  
  
  
      ret = avcodec_send_frame(enc_ctx, frame);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Error sending a frame for encoding\n");
  
          exit(1);
  
      }
  
  
  
      while (ret >= 0) {
  
          ret = avcodec_receive_packet(enc_ctx, pkt);
  
          if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
  
              return;
  
          else if (ret &lt; 0) {
  
              fprintf(stderr, "Error during encoding\n");
  
              exit(1);
  
          }
  
  
  
          printf("Write packet %3"PRId64" (size=%5d)\n", pkt->pts, pkt->size);
  
          fwrite(pkt->data, 1, pkt->size, outfile);
  
          av_packet_unref(pkt);
  
      }
  
  }
  
  
  
  int main(int argc, char **argv)
  
  {
  
      const char *filename, *codec_name;
  
      const AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int i, ret, x, y;
  
      FILE *f;
  
      AVFrame *frame;
  
      AVPacket *pkt;
  
      uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
      if (argc &lt;= 2) {
  
          fprintf(stderr, "Usage: %s <output file="file"> <codec>\n", argv[0]);
  
          exit(0);
  
      }
  
      filename = argv[1];
  
      codec_name = argv[2];
  
  
  
      /* find the mpeg1video encoder */
  
      codec = avcodec_find_encoder_by_name(codec_name);
  
      if (!codec) {
  
          fprintf(stderr, "Codec '%s' not found\n", codec_name);
  
          exit(1);
  
      }
  
  
  
      c = avcodec_alloc_context3(codec);
  
      if (!c) {
  
          fprintf(stderr, "Could not allocate video codec context\n");
  
          exit(1);
  
      }
  
  
  
      pkt = av_packet_alloc();
  
      if (!pkt)
  
          exit(1);
  
  
  
      /* put sample parameters */
  
      c->bit_rate = 400000;
  
      /* resolution must be a multiple of two */
  
      c->width = 352;
  
      c->height = 288;
  
      /* frames per second */
  
      c->time_base = (AVRational){1, 25};
  
      c->framerate = (AVRational){25, 1};
  
  
  
      /* emit one intra frame every ten frames
  
       * check frame pict_type before passing frame
  
       * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
  
       * then gop_size is ignored and the output of encoder
  
       * will always be I frame irrespective to gop_size
  
       */
  
      c->gop_size = 10;
  
      c->max_b_frames = 1;
  
      c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
      if (codec->id == AV_CODEC_ID_H264)
  
          av_opt_set(c->priv_data, "preset", "slow", 0);
  
  
  
      /* open it */
  
      ret = avcodec_open2(c, codec, NULL);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
  
          exit(1);
  
      }
  
  
  
      f = fopen(filename, "wb");
  
      if (!f) {
  
          fprintf(stderr, "Could not open %s\n", filename);
  
          exit(1);
  
      }
  
  
  
      frame = av_frame_alloc();
  
      if (!frame) {
  
          fprintf(stderr, "Could not allocate video frame\n");
  
          exit(1);
  
      }
  
      frame->format = c->pix_fmt;
  
      frame->width  = c->width;
  
      frame->height = c->height;
  
  
  
      ret = av_frame_get_buffer(frame, 32);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Could not allocate the video frame data\n");
  
          exit(1);
  
      }
  
  
  
      /* encode 1 second of video */
  
      for (i = 0; i &lt; 25; i++) {
  
          fflush(stdout);
  
  
  
          /* make sure the frame data is writable */
  
          ret = av_frame_make_writable(frame);
  
          if (ret &lt; 0)
  
              exit(1);
  
  
  
          /* prepare a dummy image */
  
          /* Y */
  
          for (y = 0; y &lt; c->height; y++) {
  
              for (x = 0; x &lt; c->width; x++) {
  
                  frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
  
              }
  
          }
  
  
  
          /* Cb and Cr */
  
          for (y = 0; y &lt; c->height/2; y++) {
  
              for (x = 0; x &lt; c->width/2; x++) {
  
                  frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
  
                  frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
  
              }
  
          }
  
  
  
          frame->pts = i;
  
  
  
          /* encode the image */
  
          encode(c, frame, pkt, f);
  
      }
  
  
  
      /* flush the encoder */
  
      encode(c, NULL, pkt, f);
  
  
  
      /* add sequence end code to have a real MPEG file */
  
      if (codec->id == AV_CODEC_ID_MPEG1VIDEO || codec->id == AV_CODEC_ID_MPEG2VIDEO)
  
          fwrite(endcode, 1, sizeof(endcode), f);
  
      fclose(f);
  
  
  
      avcodec_free_context(&amp;c);
  
      av_frame_free(&amp;frame);
  
      av_packet_free(&amp;pkt);
  
  
  
      return 0;
  
  }
  
  </codec></output>

  ffmpeg -codecs return a bunch of codecs among which libx264 and libx265. When I run the above code I get NULL from avcodec_find_encoder_by_name() :

  gt@gt-Aspire-E1-570 : /libav$ ./encode_video pippo libx264
  Codec ’libx264’ not found
  gt@gt-Aspire-E1-570 : /libav$ ./encode_video pippo x264
  Codec ’x264’ not found
  gt@gt-Aspire-E1-570 : /libav$ ./encode_video pippo H264
  Codec ’H264’ not found
  gt@gt-Aspire-E1-570 : /libav$

  Can someone help please ?

  Thanks