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• Why is there an audio delay on recording video stream with ffmpeg ?

  25 décembre 2023, par mqwerty

  I am trying to record video and audio stream (Line in Microphone Analog Audio) which are streaming from broadcaster computer with those parameters in the recorder computer ;

  


  ffmpeg record parameters :

  


  /usr/bin/ffmpeg -y -buffer_size max -thread_queue_size 8192 -i udp://225.0.5.11:1026 -buffer_size max -thread_queue_size 8192 -i udp://225.0.5.11:1032 -map 0:v -map 1:a -metadata title=COMPUTER-01_metadata_file -metadata creation_time="2023-12-25 13:25:29" -threads 0 -c:v copy -c:a copy -movflags +faststart -f segment -segment_time 01:00:00 -segment_atclocktime 1 -reset_timestamps 1 -strftime 1 -segment_format mp4 -t 120 test_record_video_with_audio_%Y-%m-%d_%H-%M-%S.mp4


  


  The ffmpeg started and finished successfully, but when I open the recorded video with mpv like (mpv test_record_video_with_audio.mp4), I realized that there is a 5-6 seconds delay in audio. How can I prevent the delay of audio in the recorded mp4 file without using offset ? My last option is setting offset but I think that it is not safe according to any changes in network or etc.

  


  FFMPEG version on both computer :

  


  ffmpeg version 4.2.9 Copyright (c) 2000-2023 the FFmpeg developers
built with gcc 8 (GCC)


  


  BROADCASTER COMPUTER :

  


  sysctl.conf :

  


  No added configurations.


  


  ethtool output :

  


  Supported ports: [ TP ]
Supported link modes:   100baseT/Full
                        1000baseT/Full
                        10000baseT/Full
                        2500baseT/Full
                        5000baseT/Full
Supported pause frame use: Symmetric
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes:  100baseT/Full
                        1000baseT/Full
                        10000baseT/Full
Advertised pause frame use: Symmetric
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Speed: 10000Mb/s
Duplex: Full
Auto-negotiation: on
Port: Twisted Pair
PHYAD: 0
Transceiver: internal
MDI-X: Unknown
Supports Wake-on: d
Wake-on: d
    Current message level: 0x00000007 (7)
                           drv probe link
Link detected: yes


  


  ffmpeg video stream :

  


  ffmpeg -fflags +genpts -f x11grab -framerate 30 -video_size uhd2160 -i :0 -c:v hevc_nvenc -preset fast -pix_fmt bgr0 -b:v 3M -g 25 -an -f mpegts udp://225.0.5.11:1026


  


  ffmpeg audio stream :

  


  ffmpeg -f alsa -i hw:0,0 -c:a aac -ar 48000 -b:a 1024K -ab 512k -f rtp_mpegts rtp://225.0.5.11:1032


  


  nvidia-smi :

  


  | NVIDIA-SMI 535.129.03             Driver Version: 535.129.03   CUDA Version: 12.2     |
|-----------------------------------------+----------------------+----------------------+
| GPU  Name                 Persistence-M | Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp   Perf          Pwr:Usage/Cap |         Memory-Usage | GPU-Util  Compute M. |
|                                         |                      |               MIG M. |
|=========================================+======================+======================|
|   0  NVIDIA T400 4GB                Off | 00000000:5B:00.0 Off |                  N/A |
| 38%   38C    P8              N/A /  31W |    207MiB /  4096MiB |      0%      Default |
|                                         |                      |                  N/A |
+-----------------------------------------+----------------------+----------------------+
|   1  NVIDIA RTX A4000               Off | 00000000:9E:00.0 Off |                  Off |
| 41%   59C    P2              41W / 140W |    766MiB / 16376MiB |     17%      Default |
|                                         |                      |                  N/A |
+-----------------------------------------+----------------------+----------------------+
                                                                                         
+---------------------------------------------------------------------------------------+
| Processes:                                                                            |
|  GPU   GI   CI        PID   Type   Process name                            GPU Memory |
|        ID   ID                                                             Usage      |
|=======================================================================================|
|    0   N/A  N/A      3227      G   /usr/libexec/Xorg                           114MiB |
|    0   N/A  N/A      3423      G   /usr/bin/gnome-shell                         87MiB |
|    1   N/A  N/A      3227      G   /usr/libexec/Xorg                           285MiB |
|    1   N/A  N/A      3423      G   /usr/bin/gnome-shell                         91MiB |
|    1   N/A  N/A      3762      C   ffmpeg                                      372MiB |
+---------------------------------------------------------------------------------------+


  


  lscpu output :

  


  

Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
CPU(s):              96
On-line CPU(s) list: 0-95
Thread(s) per core:  2
Core(s) per socket:  24
Socket(s):           2
NUMA node(s):        2
Vendor ID:           GenuineIntel
BIOS Vendor ID:      Intel(R) Corporation
CPU family:          6
Model:               85
Model name:          Intel(R) Xeon(R) Gold 5220R CPU @ 2.20GHz
BIOS Model name:     Intel(R) Xeon(R) Gold 5220R CPU @ 2.20GHz
Stepping:            7
CPU MHz:             2200.000
CPU max MHz:         4000.0000
CPU min MHz:         1000.0000
BogoMIPS:            4400.00
Virtualization:      VT-x
L1d cache:           32K
L1i cache:           32K
L2 cache:            1024K
L3 cache:            36608K
NUMA node0 CPU(s):   0-23,48-71
NUMA node1 CPU(s):   24-47,72-95


  


  OS : CentOS Stream release 8


  


  RECORDER COMPUTER :

  


  sysctl.conf :

  


  net.core.rmem_max=16777216
net.core.wmem_max=16777216
net.ipv4.tcp_rmem= 4096 87380 16777216
net.ipv4.tcp_wmem= 4096 65536 16777216
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_timestamps = 1
net.ipv4.tcp_sack = 1
net.ipv4.tcp_no_metrics_save = 0
net.core.netdev_max_backlog = 50000
net.core.optmem_max=25165824


  


  lscpu output :

  


  Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
CPU(s):              96
On-line CPU(s) list: 0-95
Thread(s) per core:  2
Core(s) per socket:  24
Socket(s):           2
NUMA node(s):        2
Vendor ID:           GenuineIntel
BIOS Vendor ID:      Intel
CPU family:          6
Model:               106
Model name:          Intel(R) Xeon(R) Gold 5318Y CPU @ 2.10GHz
BIOS Model name:     Intel(R) Xeon(R) Gold 5318Y CPU @ 2.10GHz
Stepping:            6
CPU MHz:             3400.000
CPU max MHz:         3400.0000
CPU min MHz:         800.0000
BogoMIPS:            4200.00
Virtualization:      VT-x
L1d cache:           48K
L1i cache:           32K
L2 cache:            1280K
L3 cache:            36864K


  


  ethtool output :

  


  Supported ports: [ TP ]
    Supported link modes:   1000baseT/Full
                            10000baseT/Full
    Supported pause frame use: Symmetric Receive-only
    Supports auto-negotiation: Yes
    Supported FEC modes: Not reported
    Advertised link modes:  1000baseT/Full
                            10000baseT/Full
    Advertised pause frame use: Symmetric
    Advertised auto-negotiation: Yes
    Advertised FEC modes: Not reported
    Speed: 10000Mb/s
    Duplex: Full
    Auto-negotiation: on
    Port: Twisted Pair
    PHYAD: 12
    Transceiver: internal
    MDI-X: Unknown
    Supports Wake-on: d
    Wake-on: d
        Current message level: 0x00002081 (8321)
                               drv tx_err hw
    Link detected: yes


  


  No NVIDIA Graphic Driver

  


  OS : CentOS Stream release 8


  


  I tried audio encoding while recording like :

  


  "-c:a", "aac",  
"-ar", "48000", 
"-b:a", "128k",


  


  I also tried :

  


  "aresample=async=1"



  


  Unfortunately,these did not have any improvements on preventing latency in audio.

  


• How to read a UDP stream and forward it as SRT ?

  27 décembre 2020, par andrea-f

  During this holidays I started a small hobby project to learn how SRT works. I got a simple Android app set up with NodeMediaClient (https://github.com/NodeMedia/NodeMediaClient-Android/tree/master/nodemediaclient/src) which publishes an UDP stream, which I read by :

  


       private final Object txFrameLock = new Object();
     [...]

     t = new Thread(new Runnable() {
        public void run() {

            byte[] message = new byte[MAX_UDP_DATAGRAM_LEN];

            try {
                socket = new DatagramSocket(UDP_SERVER_PORT);
                while (!Thread.currentThread().isInterrupted()) {
                    while (!socket.isClosed()) {
                        DatagramPacket packet = new DatagramPacket(message, message.length);
                        socket.receive(packet);
                       
                        ByteBuffer tsUDPPack = ByteBuffer.wrap(packet.getData());
                        int ret = parseTSPack(tsUDPPack);
                        
                        Log.i("srtstreaming SRT packet sent", String.format("%d", ret));
                    }
                    synchronized (txFrameLock) {
                        try {
                            txFrameLock.wait(10);
                            //Thread.sleep(500);

                        } catch (InterruptedException ie) {
                            t.interrupt();
                        }
                    }
                }

            } catch (SocketException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (socket != null) {
                    socket.close();
                }
            }
        }
    });
    t.start();


  


  parseTSPack looks like :

  


      private int parseTSPack(ByteBuffer tsUDPPack)
    {
        byte[] ts_pack = new byte[TS_PACK_LEN];
        if (tsUDPPack.remaining() != TS_UDP_PACK_LEN) {
            Log.i(TAG, "srtestreaming ts udp len is not 1316.");
            return 0;
        }
        int count = 0;
        while (tsUDPPack.remaining() > 0) {
            tsUDPPack.get(ts_pack);
            int ret = mSrt.send(ts_pack);
            count++;
            Log.i("srtstreaming ts packets ", String.format("%d", count));
        }
        return count;
    }


  


  Then the JNI implementation takes care of opening the stream (srt://192.168.1.238:4200?streamid=test/live/1234) and then handling the mSrt.send(ts_pack) call to forward the packets to SRT caller.
On the receiving side I am using : ffmpeg -v 9 -loglevel 99 -report -re -i 'srt://192.168.1.238:4200?streamid=test/live/1234&mode=listener' -c copy -copyts -f mpegts ./srt_recording_ffmpeg.ts the video arrives broken and no frames can be decoded.
In FFMPEG output I am getting something along the lines :

  


  [mpegts @ 0x7f9a0f008200] Probe: 176, score: 1, dvhs_score: 1, fec_score: 1 
[mpegts @ 0x7f9a0f008200] Probe: 364, score: 2, dvhs_score: 1, fec_score: 1 
[mpegts @ 0x7f9a0f008200] Probe: 552, score: 3, dvhs_score: 1, fec_score: 1 
[mpegts @ 0x7f9a0f008200] Probe: 740, score: 3, dvhs_score: 1, fec_score: 1 
[mpegts @ 0x7f9a0f008200] Packet corrupt (stream = 1, dts = 980090).
[mpegts @ 0x7f9a0f008200] rfps: 7.583333 0.011807
[mpegts @ 0x7f9a0f008200] rfps: 8.250000 0.014541
[...]
[mpegts @ 0x7f9a10809000] Non-monotonous DTS in output stream 0:1; previous: 1193274, current: 1189094; changing to 1193275. This may result in incorrect timestamps in the output file.
[mpegts @ 0x7f9a10809000] Non-monotonous DTS in output stream 0:1; previous: 1199543, current: 1199543; changing to 1199544. This may result in incorrect timestamps in the output file.


  


  Any ideas how to correctly forward the udp packets to the SRT library ?

  


• angular cli 6 fluent-ffmpeg cannot get to run ? Core node plugins fs,ps,child_process runtime errors

  9 septembre 2018, par user6041243

  Just created new angular cli app 6. Did a npm install ffmpeg. First is says it can’t resolve (child_process, fs, path). Add those to browser with false in package.json. Builds but then get runtime errors in ffmpeg when I run it http://localhost:4200 in browser when it tries to do a method of fs or path because function doesn’t exist. Just wanting to know how to get ffmpeg or fluent-ffmpeg working in an angular cli project. Has anyone does this ? Any examples.

  Seems like the fs, os, path, child_process aren’t available in browser ? Can ffmpeg node plugin be run in browser. Would like to run a statis web app with this on local machine running local ffmpeg executable.

  Can this be done ?