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• ffmpeg takes a while to start

  17 octobre 2020, par Suspended

  I have this command in python script, in a loop :

  


  ffmpeg -i somefile.mp4 -ss 00:03:12 -t 00:00:35 piece.mp4 -loglevel error -stats


  


  It cuts out pieces of input file (-i). Input filename, as well as start time (-ss) and length of the piece I cut out (-t) varies, so it reads number of mp4 files and cuts out number of pieces from each one. During execution of the script it might be called around 100 times. My problem is that each time before it starts, there is a delay of few seconds and it adds up to significant time. How can I get it to start immediately ?

  


  The script (process_videos.py) :
  

  


  import subprocess
import sys
import math
import time

class TF:
    """TimeFormatter class (TF).
This class' reason for being is to convert time in short
form, e.g. 1:33, 0:32, or 23 into long form accepted by
mp4cut function in bash, e.g. 00:01:22, 00:00:32, etc"""

def toLong(self, shrt):
    """Converts time to its long form"""
    sx = '00:00:00'
    ladd = 8 - len(shrt)
    n = sx[:ladd] + shrt
    return n

def toShort(self, lng):
    """Converts time to short form"""
    if lng[0] == '0' or lng[0] == ':':
        return self.toShort(lng[1:])
    else:
        return lng

def toSeconds(self, any_time):
    """Converts time to seconds"""
    if len(any_time) < 3:
        return int(any_time)
    tt = any_time.split(':')
    if len(any_time) < 6:            
        return int(tt[0])*60 + int(tt[1])
    return int(tt[0])*3600 + int(tt[1])*60 + int(tt[2])

def toTime(self, secsInt):
    """"""
    tStr = ''
    hrs, mins, secs = 0, 0, 0
    if secsInt >= 3600:
        hrs = math.floor(secsInt / 3600)
        secsInt = secsInt % 3600
    if secsInt >= 60:
        mins = math.floor(secsInt / 60)
        secsInt = secsInt % 60
    secs = secsInt
    return str(hrs).zfill(2) + ':' + str(mins).zfill(2) + ':' + str(secs).zfill(2)

def minus(self, t_start, t_end):
    """"""
    t_e = self.toSeconds(t_end)
    t_s = self.toSeconds(t_start)
    t_r = t_e - t_s
    hrs, mins, secs = 0, 0, 0
    if t_r >= 3600:
        hrs = math.floor(t_r / 3600)
        t_r = t_r - (hrs * 3600)
    if t_r >= 60:
        mins = math.floor(t_r / 60)
        t_r = t_r - (mins * 60)
    secs = t_r
    hrsf = str(hrs).zfill(2)
    minsf = str(mins).zfill(2)
    secsf = str(secs).zfill(2)
    t_fnl = hrsf + ':' + minsf + ':' + secsf
    return t_fnl

def go_main():
    tf = TF()
    vid_n = 0
    arglen = len(sys.argv)
    if arglen == 2:
        with open(sys.argv[1], 'r') as f_in:
            lines = f_in.readlines()
            start = None
            end = None
            cnt = 0
            for line in lines:
                if line[:5] == 'BEGIN':
                    start = cnt
                if line[:3] == 'END':
                    end = cnt
                cnt += 1
            if start == None or end == None:
                print('Invalid file format. start = {}, end = {}'.format(start,end))
                return
            else:
                lines_r = lines[start+1:end]
                del lines
                print('videos to process: {}'.format(len(lines_r)))
                f_out_prefix = ""
                for vid in lines_r:
                     vid_n += 1
                    print('\nProcessing video {}/{}'.format(vid_n, len(lines_r)))
                    f_out_prefix = 'v' + str(vid_n) + '-'
                    dat = vid.split('!')[1:3]
                    title = dat[0]
                    dat_t = dat[1].split(',')
                    v_pieces = len(dat_t)
                    piece_n = 0
                    video_pieces = []
                    cmd1 = "echo -n \"\" > tmpfile"
                    subprocess.run(cmd1, shell=True)                    
                    print('  new tmpfile created')
                    for v_times in dat_t:
                        piece_n += 1
                        f_out = f_out_prefix + str(piece_n) + '.mp4'
                        video_pieces.append(f_out)
                        print('  piece filename {} added to video_pieces list'.format(f_out))
                        v_times_spl = v_times.split('-')
                        v_times_start = v_times_spl[0]
                        v_times_end = v_times_spl[1]
                        t_st = tf.toLong(v_times_start)
                        t_dur = tf.toTime(tf.toSeconds(v_times_end) - tf.toSeconds(v_times_start))
                        cmd3 = ["ffmpeg", "-i", title, "-ss", t_st, "-t", t_dur, f_out, "-loglevel", "error", "-stats"]
                        print('  cutting out piece {}/{} - {}'.format(piece_n, len(dat_t), t_dur))
                        subprocess.run(cmd3)
                    for video_piece_name in video_pieces:
                        cmd4 = "echo \"file " + video_piece_name + "\" >> tmpfile"
                        subprocess.run(cmd4, shell=True)
                        print('  filename {} added to tmpfile'.format(video_piece_name))
                    vname = f_out_prefix[:-1] + ".mp4"
                    print('  name of joined file: {}'.format(vname))
                    cmd5 = "ffmpeg -f concat -safe 0 -i tmpfile -c copy joined.mp4 -loglevel error -stats"
                    to_be_joined = " ".join(video_pieces)
                    print('  joining...')
                    join_cmd = subprocess.Popen(cmd5, shell=True)
                    join_cmd.wait()
                    print('  joined!')
                    cmd6 = "mv joined.mp4 " + vname
                    rename_cmd = subprocess.Popen(cmd6, shell=True)
                    rename_cmd.wait()
                    print('  File joined.mp4 renamed to {}'.format(vname))
                    cmd7 = "rm " + to_be_joined
                    rm_cmd = subprocess.Popen(cmd7, shell=True)
                    rm_cmd.wait()
                    print('rm command completed - pieces removed')
                cmd8 = "rm tmpfile"
                subprocess.run(cmd8, shell=True)
                print('tmpfile removed')
                print('All done')
    else:
        print('Incorrect number of arguments')

############################
if __name__ == '__main__':
    go_main()


  


  process_videos.py is called from bash terminal like this :

  


  $ python process_videos.py video_data   


  


  video_data file has the following format :

  


  BEGIN
!first_video.mp4!3-23,55-1:34,2:01-3:15,3:34-3:44!
!second_video.mp4!2-7,12-44,1:03-1:33!
END


  


  My system details :

  


  System:    Host: snowflake Kernel: 5.4.0-52-generic x86_64 bits: 64 Desktop: Gnome 3.28.4
           Distro: Ubuntu 18.04.5 LTS
Machine:   Device: desktop System: Gigabyte product: N/A serial: N/A
Mobo:      Gigabyte model: Z77-D3H v: x.x serial: N/A BIOS: American Megatrends v: F14 date: 05/31/2012
CPU:       Quad core Intel Core i5-3570 (-MCP-) cache: 6144 KB 
           clock speeds: max: 3800 MHz 1: 1601 MHz 2: 1601 MHz 3: 1601 MHz 4: 1602 MHz
Drives:    HDD Total Size: 1060.2GB (55.2% used)
           ID-1: /dev/sda model: ST31000524AS size: 1000.2GB
           ID-2: /dev/sdb model: Corsair_Force_GT size: 60.0GB
Partition: ID-1: / size: 366G used: 282G (82%) fs: ext4 dev: /dev/sda1
           ID-2: swap-1 size: 0.70GB used: 0.00GB (0%) fs: swap dev: /dev/sda5
Info:      Processes: 313 Uptime: 16:37 Memory: 3421.4/15906.9MB Client: Shell (bash) inxi: 2.3.56


  


• FFMPEG RTSP stream to MPEG4/H264 file using libx264

  16 octobre 2020, par Phi

  Heyo folks,

  



  I'm attempting to transcode/remux an RTSP stream in H264 format into a MPEG4 container, containing just the H264 video stream. Basically, webcam output into a MP4 container.

  



  I can get a poorly coded MP4 produced, using this code :

  



  // Variables here for demo
AVFormatContext * video_file_output_format = nullptr;
AVFormatContext * rtsp_format_context = nullptr;
AVCodecContext * video_file_codec_context = nullptr;
AVCodecContext * rtsp_vidstream_codec_context = nullptr;
AVPacket packet = {0};
AVStream * video_file_stream = nullptr;
AVCodec * rtsp_decoder_codec = nullptr;
int errorNum = 0, video_stream_index = 0;
std::string outputMP4file = "D:\\somemp4file.mp4";

// begin
AVDictionary * opts = nullptr;
av_dict_set(&opts, "rtsp_transport", "tcp", 0);

if ((errorNum = avformat_open_input(&rtsp_format_context, uriANSI.c_str(), NULL, &opts)) < 0) {
    errOut << "Connection failed: avformat_open_input failed with error " << errorNum << ":\r\n" << ErrorRead(errorNum);
    TacticalAbort();
    return;
}

rtsp_format_context->max_analyze_duration = 50000;
if ((errorNum = avformat_find_stream_info(rtsp_format_context, NULL)) < 0) {
    errOut << "Connection failed: avformat_find_stream_info failed with error " << errorNum << ":\r\n" << ErrorRead(errorNum);
    TacticalAbort();
    return;
}

video_stream_index = errorNum = av_find_best_stream(rtsp_format_context, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);

if (video_stream_index < 0) {
    errOut << "Connection in unexpected state; made a connection, but there was no video stream.\r\n"
        "Attempts to find a video stream resulted in error " << errorNum << ": " << ErrorRead(errorNum);
    TacticalAbort();
    return;
}

rtsp_vidstream_codec_context = rtsp_format_context->streams[video_stream_index]->codec;

av_init_packet(&packet);

if (!(video_file_output_format = av_guess_format(NULL, outputMP4file.c_str(),  NULL))) {
    TacticalAbort();
    throw std::exception("av_guess_format");
}

if (!(rtsp_decoder_codec = avcodec_find_decoder(rtsp_vidstream_codec_context->codec_id))) {
    errOut << "Connection failed: connected, but avcodec_find_decoder returned null.\r\n"
        "Couldn't find codec with an AV_CODEC_ID value of " << rtsp_vidstream_codec_context->codec_id << ".";
    TacticalAbort();
    return;
}

video_file_format_context = avformat_alloc_context();
video_file_format_context->oformat = video_file_output_format;

if (strcpy_s(video_file_format_context->filename, sizeof(video_file_format_context->filename), outputMP4file.c_str())) {
    errOut << "Couldn't open video file: strcpy_s failed with error " << errno << ".";
    std::string log = errOut.str();
    TacticalAbort();
    throw std::exception("strcpy_s");
}

if (!(video_file_encoder_codec = avcodec_find_encoder(video_file_output_format->video_codec))) {
    TacticalAbort();
    throw std::exception("avcodec_find_encoder");
}

// MARKER ONE

if (!outputMP4file.empty() &&
    !(video_file_output_format->flags & AVFMT_NOFILE) &&
    (errorNum = avio_open2(&video_file_format_context->pb, outputMP4file.c_str(), AVIO_FLAG_WRITE, nullptr, &opts)) < 0) {
    errOut << "Couldn't open video file \"" << outputMP4file << "\" for writing : avio_open2 failed with error " << errorNum << ": " << ErrorRead(errorNum);
    TacticalAbort();
    return;
}

// Create stream in MP4 file
if (!(video_file_stream = avformat_new_stream(video_file_format_context, video_file_encoder_codec))) {
    TacticalAbort();
    return;
}

AVCodecContext * video_file_codec_context = video_file_stream->codec;

// MARKER TWO

// error -22/-21 in avio_open2 if this is skipped
if ((errorNum = avcodec_copy_context(video_file_codec_context, rtsp_vidstream_codec_context)) != 0) {
    TacticalAbort();
    throw std::exception("avcodec_copy_context");
}

//video_file_codec_context->codec_tag = 0;

/*
// MARKER 3 - is this not needed? Examples suggest not.
if ((errorNum = avcodec_open2(video_file_codec_context, video_file_encoder_codec, &opts)) < 0)
{
    errOut << "Couldn't open video file codec context: avcodec_open2 failed with error " << errorNum << ": " << ErrorRead(errorNum);
    std::string log = errOut.str();
    TacticalAbort();
    throw std::exception("avcodec_open2, video file");
}*/

//video_file_format_context->flags |= AVFMT_FLAG_GENPTS;
if (video_file_format_context->oformat->flags & AVFMT_GLOBALHEADER)
{
    video_file_codec_context->flags |= CODEC_FLAG_GLOBAL_HEADER;
}

if ((errorNum = avformat_write_header(video_file_format_context, &opts)) < 0) {
    errOut << "Couldn't open video file: avformat_write_header failed with error " << errorNum << ":\r\n" << ErrorRead(errorNum);
    std::string log = errOut.str();
    TacticalAbort();
    return;
}


  



  However, there are several issues :

  



  

  1. I can't pass any x264 options to the output file. The output H264 matches the input H264's profile/level - switching cameras to a different model switches H264 level.

  


  2. The timing of the output file is off, noticeably.

  


  3. The duration of the output file is off, massively. A few seconds of footage becomes hours, although playtime doesn't match. (FWIW, I'm using VLC to play them.)

  


  



  Passing x264 options

  



  If I manually increment PTS per packet, and set DTS equal to PTS, it plays too fast, 2-3 seconds' worth of footage in one second playtime, and duration is hours long. The footage also blurs past several seconds, about 10 seconds' footage in a second.

  



  If I let FFMPEG decide (with or without GENPTS flag), the file has a variable frame rate (probably as expected), but it plays the whole file in an instant and has a long duration too (over forty hours for a few seconds). The duration isn't "real", as the file plays in an instant.

  



  At Marker One, I try to set the profile by passing options to avio_open2. The options are simply ignored by libx264. I've tried :

  



  av_dict_set(&opts, "vprofile", "main", 0);
av_dict_set(&opts, "profile", "main", 0); // error, missing '('
// FF_PROFILE_H264_MAIN equals 77, so I also tried
av_dict_set(&opts, "vprofile", "77", 0); 
av_dict_set(&opts, "profile", "77", 0);


  



  It does seem to read the profile setting, but it doesn't use them. At Marker Two, I tried to set it after the avio_open2, before avformat_write_header .

  



  // I tried all 4 av_dict_set from earlier, passing it to avformat_write_header.
// None had any effect, they weren't consumed.
av_opt_set(video_file_codec_context, "profile", "77", 0);
av_opt_set(video_file_codec_context, "profile", "main", 0);
video_file_codec_context->profile = FF_PROFILE_H264_MAIN;
av_opt_set(video_file_codec_context->priv_data, "profile", "77", 0);
av_opt_set(video_file_codec_context->priv_data, "profile", "main", 0);


  



  Messing with privdata made the program unstable, but I was trying anything at that point.
I'd like to solve issue 1 with passing settings, since I imagine it'd bottleneck any attempt to solve issues 2 or 3.

  



  I've been fiddling with this for the better part of a month now. I've been through dozens of documentation, Q&As, examples. It doesn't help that quite a few are outdated.

  



  Any help would be appreciated.

  



  Cheers

  


• avformat/mpegtsenc : Changed Video PES packet length to 0.

  12 avril 2014, par Graham Booker

  avformat/mpegtsenc : Changed Video PES packet length to 0.
  The rational for this is another issue that plex has exposed.  When it is
  
  conducting a transcode of video to HLS for streaming, my father noticed
  
  artifacts when played on his GoogleTV (NSZ-GT1).  He sent me a test file
  
  and I reproduced it on my device of the same model.  It is important to
  
  note that the artifacts were not present when streaming to VLC or QuickTime
  
  Player.  I copied the command-line that plex used, and conducted all of the
  
  following tests using FFmpeg git.
  Transcode to HLS : artifacts on playback
  
  Transcode to TS : playback is fine
  
  Cat HLS segments into a single TS : playback is fine
  
  Segment single TS file to segments : artifacts on playback
  
  Segment single TS file to segments using Apple’s HLS segmenter : playback is
  
  fine
  At this point I carefully examined the differences between Apple’s HLS
  
  segmenter output and FFmpeg’s.  Among the considerable differences, I
  
  noticed that the video PES packets always had a 0 length.  So I continued :
  Transcode to HLS using FFmpeg with 0 length PES packets : playback is fine.
  
  Segment single TS to segments with 0 length PES packets : playback is fine.
  All failures mentioned are only on the GTV since it is the only player on
  
  which I could reproduce artifacts.  I only tested the GTV, VLC, and
  
  QuickTime Player though, so my test case is limited.  I do not know if
  
  other players exhibit this issue.
  Since it was useful last time, I have uploaded the test file as
  
  hls_pes_packet_length.m4v along with its associated txt file which contains
  
  the transcode command-line that was used.
  Reviewed-by : Kieran Kunhya <kierank@obe.tv>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/mpegtsenc.c
  • [DH] tests/ref/lavf/ts