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• Gnuplot how to set a variable to standard-input if not passed

  27 août 2020, par DDS

  I have a gnuplot script (plot.script) that is invoked like

  


  C:> ffmpeg -i '.\my_awesome_audio_file.wav' -filter_complex aformat=channel_layouts=mono -acodec pcm_s16le -ar 4000 -f data - | gnuplot -e "fileout='plot';fileformat='png';wid=500;" .\plot.script        


  


  Now I'd want to default filein variable to stdin if it is not passed as argument. This because I want to be able to call this script as a 1-liner command with ffmpeg data generation and also as step-by-step procedure

  


  My idea was to use

  


  if(!exists('filein')){
filein = '-';
}


  


  but this throws warning: Skipping data file with no valid points

  


  if i print the variable datafile I got - (I expected something like stdin).

  


  this is the plot.script script :

  


  
if(!exists('filein')){
    filein = '-';
    }

if (!exists("hei")){
    hei = 4444;
    }
if (!exists("wid")){
    wid = 5555;
    }
if(!exists("fileformat")){
     fileformat = 'png';
     }
if(!exists("fileout")){
     fileout = 'risultato';
   }
   
fileout = fileout . '.' . fileformat;
   
if(!exists("dataformat")){
    dataformat = '%int16';
    }
if(fileformat eq 'png'){
  set terminal png transparent size larghezza,altezza;
  
  }else{
  set terminal fileformat size wid,hei;
  }
  set output fileout;
  unset key;
  unset tics;
  unset border;
  set lmargin 0;
  set rmargin 0;
  set tmargin 0;
  set bmargin 0;


print filein;
plot filein binary filetype=bin format=dataformat endian=little array=1:0 with lines linecolor "0x009900";


  


  But I also want to call this command-by-command :
generate the data-file :

  


  c:> ffmpeg -i '.\my_awesome_audio_file.wav' -filter_complex aformat=channel_layouts=mono -acodec pcm_s16le -ar 4000 -f data audio.dat


  


  plot the data :

  


  c:> gnuplot -e "filein='audio.dat';fileout='plot';fileformat='png';wid=500;" .\plot.script


  


• libav sws_scale() fails colorspace conversion on real device, works on emulator

  26 août 2020, par chugadie

  I'm making a movie player with libav. I have decoding video packets working, I have play in reverse working, I have seeking working. All this works no an x86 android emulator, but fails to work on a real android phone (arm64-v8a)

  


  The failure is in sws_scale() - it returns 0. The video frames continue to be decoded properly with no errors.

  


  There are no errors, warnings, alerts from libav. I have connected an avlog_callback

  


  void log_callback(void *ptr, int level, const char *fmt, va_list vargs) {
    if (level<= AV_LOG_WARNING)
        __android_log_print( level, LOG_TAG, fmt, vargs);
}
uint64_t openMovie( char* path, int rotate, float javaDuration )
{
    av_log_set_level(AV_LOG_WARNING);
    av_log_set_callback(log_callback);


  


  The code to do the sws_scale() is :

  


  int JVM_getBitmapBuffer( JNIEnv* env, jobject thiz, jlong av, jobject bufferAsInt, jbyte transparent ) { 
    avblock *block = (avblock *) av;
    if (!block) {
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  avblock is null");
        return AVERROR(EINVAL);
    }
    if (!block->pCodecCtx) {
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  codecctx is null");
        return AVERROR(EINVAL);
    }

    int width = block->pCodecCtx->width;
    int height = block->pCodecCtx->height;

    if (NULL == block->sws) {
        __android_log_print( ANDROID_LOG_ERROR, LOG_TAG, "getBitmapBuffer:\n  *** invalid sws context ***" );
    }

    int scaleRet = sws_scale( block->sws,
            block->pFrame->data,
            block->pFrame->linesize,
            0,
            height,
            block->pFrameRGB->data,
            block->pFrameRGB->linesize
    );
    if (scaleRet == 0 ) {
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  scale failed");
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  pframe linesize    %d", block->pFrame->linesize[0]); 
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  pframergb linesize %d", block->pFrameRGB->linesize[0]); 
        __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, "  height  %d",
        height);
        return AVERROR(EINVAL);
    }


  


  Setting up the codex and avframes :

  


  //i have tried every combination of 1, 8, 16, and 32 for these values
int alignRGB = 32;
int align    = 16; 
int width    = block->pCodecCtx->width;
int height   = block->pCodecCtx->height;
block->pFrame    = av_frame_alloc();
block->pFrameRGB = av_frame_alloc();

block->pFrameRGBBuffer = av_malloc(
    (size_t)av_image_get_buffer_size(AV_PIX_FMT_RGB32, width, height, alignRGB) 
);

av_image_fill_arrays(
    block->pFrameRGB->data,
    block->pFrameRGB->linesize,
    block->pFrameRGBBuffer,
    AV_PIX_FMT_RGB32,
    width,
    height,
    alignRGB
);

block->pFrameBuffer = av_malloc(
        (size_t) av_image_get_buffer_size(block->pCodecCtx->pix_fmt,
                                          width, height, align
        )
);
av_image_fill_arrays(
    block->pFrame->data,
    block->pFrame->linesize,
    block->pFrameBuffer,
    block->pCodecCtx->pix_fmt,
    width, height,
    align
);
block->sws = sws_getContext(
    width, height,
    AV_PIX_FMT_YUV420P,
    width, height,
    AV_PIX_FMT_RGB32,
    SWS_BILINEAR, NULL, NULL, 0
);


  


  Wildcards are that :

  


  

  • I'm using React-Native

  


  • My emulator is x86 android api 28

  


  • My real-device is arm64-v8a AOSP (around api 28, don't remember exactly(

  


  


  Other notes :

  


  

  • libav .so files are compiled from mobile-ffmpeg project.

  


  • I can also sws_scale also works on x86_64 linux using SDL to project YV12

  


  • Test video is here : https://github.com/markkimsal/video-thumbnailer/tree/master/fixtures

  


  • block is a simple C struct with pointers to relevant AV memory structures.

  


  • Using FFMPEG 4.3.2

  


  


  I'm pretty certain it has something to do with the pixel alignment. But documentation is practically non-existent on this topic. It could also be the difference between pixel formats RGBA and RGB32, or possibly little-endian vs big-endian.

  


• ffmpeg audio and video gradually go out of sync when recorded with shell script and make

  6 août 2020, par cgmil

  I wrote the following shell script for making streamcasts for recording streams using ffmpeg :

  


  [ -z $1 ] && { echo "No recording device selected!" 2>&1 && exit ; } || DEV=$1
VIDFILE=video/bvid.mkv
AUDFILE=audio/baud.wav
DIM=$(xdpyinfo | grep dimensions: | awk '{print $2;}')
(sleep 10 && echo "Streaming...") &
ffmpeg -nostdin -loglevel panic -f x11grab -s $DIM -i $DISPLAY.0 -c:v libx264 "$VIDFILE" &
ffmpeg -nostdin -loglevel panic -f alsa -i hw:$DEV -c:a libmp3lame  "$AUDFILE" &
sleep 1
[ -f $VIDFILE ] && (echo "Created video" 1>&2) || (echo "No video!" 1>&2)
sleep 1
[ -f $AUDFILE ] && (echo "Created audio" 1>&2) || (echo "No audio!" 1>&2)

wait
trap "killall background -s 2" SIGINT


  


  This produces a video and audio file that can then be used to make a stream via make using the command make stream. Here is the Makefile (note that there is a 3-minute long audio file and a file with images that is used to make an opening splash screen) :

  


  FULLAUDIO=audio/full.wav
AUDSTART=84
TITLE="Stats Aside:\\nInterpreting\\nProbability"
SIZEW=1920
SIZEH=1080

audio/clip.wav : $(FULLAUDIO)
        ffmpeg -ss $(AUDSTART) -i $< -t 6 -af "afade=t=in:st=0:d=3:curve=qsin,afade=t=out:st=3:d=3:curve=qsin" -c:a libmp3lame $@

img/thumb.png : img/bg.png img/ico.png
        convert -stroke white -fill white -background black -transparent "#000000" \
                 -font "URWBookman-Light" -gravity Center -size 928x1080 \
                label:$(TITLE) png:- | composite -gravity west -geometry +64+0 - \
                img/bg.png $@
        convert img/ico.png -transparent "#ffffff" png:- | composite \
                 -gravity southeast -geometry +32+32 - $@ $@
        convert $@ -resize $(SIZEW)x$(SIZEH) $@

video/intro.mp4 : img/thumb.png audio/clip.wav
        ffmpeg -i audio/clip.wav -loop 1 -t 6 -i img/thumb.png -vf "fade=t=in:st=0:d=1,fade=t=out:st=5:d=1:c=white,scale=$(SIZEW):$(SIZEH)" -c:v libx264 -c:a libmp3lame $@

ProbabilityInterpretation.mp4 : video/bvid.mkv video/intro.mp4 audio/baud.wav
        ffmpeg -i video/intro.mp4 -ss 11 -i video/bvid.mkv \
                 -ss 10 -i audio/baud.wav \
                 -filter_complex \
                "[1]fade=t=in:st=0:d=1:c=white,scale=$(SIZEW):$(SIZEH)[bvid];\
                 [2]afftdn=nr=20[baud];\
                 [0:v][0:a][bvid][baud]concat=n=2:v=1:a=1[v][a]" -map "[v]" -map "[a]" \
                 -c:v libx264 -c:a libmp3lame $@

stream : ProbabilityInterpretation.mp4

clean:
        -rm ProbabilityInterpretation.mp4
        -rm video/intro.mp4
        -rm audio/clip.wav
        -rm img/thumb.png

veryclean:
        make clean
        -rm video/bvid.mkv
        -rm audio/baud.wav



  


  Because of lag between my webcam and what appears on screen, I do intentionally start the video and audio at different times so that they can eventually become in sync. However, the end result is a video that starts with the video and audio synced together, but eventually become out of sync, with the video lagging well behind the audio. Here is a link to the video with the end result ; it's long, but notice that the video starts in sync and ends out-of-sync. I should probably also note that the operating system is living in a virtual machine (VirtualBox).

  


  Why is this happening and what can I do to prevent or correct ?