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• FFMpeg embedding .srt file into hls stream playlist as WebVTT

  11 mai 2020, par user1503606

  I had an srt subtitle file see below.

  



  1
00:00:06,840 --> 00:00:10,320
once long ago in the deep blue below

2
00:00:12,360 --> 00:00:14,370
Don't be silly, Gran Mother

3
00:00:14,870 --> 00:00:16,700
Everybody knows there's no such thing as

4
00:00:16,700 --> 00:00:17,200
Mermaids

5
00:00:17,620 --> 00:00:21,570
You wouldn't say that if you has meet one. You've meet a Mermaid

6
00:00:24,250 --> 00:00:25,180
This just came in

7
00:00:25,480 --> 00:00:26,630
I wanted to take priority

8
00:00:27,180 --> 00:00:28,500
And we followed stories like this before

9
00:00:28,640 --> 00:00:31,620
Would witches working mummies. No not like this

10
00:00:31,630 --> 00:00:33,190
Hundreds of people are testifying

11
00:00:33,370 --> 00:00:34,600
Welcome to Mississippi

12
00:00:42,390 --> 00:00:47,270
There's a powerful magic in you the spirit of the ocean

13
00:00:47,690 --> 00:00:53,940
Let me introduce you to your dreams, The Little Mermaid, off the Mississippi

14
00:01:01,880 --> 00:01:03,580
She was so beautiful

15
00:01:04,040 --> 00:01:05,270
And I know she was real

16
00:01:07,850 --> 00:01:08,550
I'm skeptical

17
00:01:13,460 --> 00:01:14,410
You shouldn't be here

18
00:01:17,560 --> 00:01:24,130
Mermaids do not exist

19
00:01:31,420 --> 00:01:34,300
Look isn't it beautiful? Sorry I have to go.

20
00:01:35,340 --> 00:01:48,570
Elizabeth, How can this be? It's Lock he knows i'm here he summoned me.

21
00:01:48,570 --> 00:01:50,570
We have to save here.

22
00:02:03,570 --> 00:02:05,570
Here soul is mine

23
00:02:05,570 --> 00:02:06,570
Take it

24
00:02:10,570 --> 00:02:12,570
It's the only way

25
00:02:15,000 --> 00:02:17,570
I believe

26
00:02:23,000 --> 00:02:25,570
Mississippi has always been magic

27
00:02:36,000 --> 00:02:38,000
Elizabeth please


  



  If I use AWS Media convert to add this to my playlist it outputs the following.

  



  #EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:300
#EXT-X-MEDIA-SEQUENCE:1
#EXT-X-PLAYLIST-TYPE:VOD
#EXTINF:170,
masterCaptionsEnglish/English.vtt
#EXT-X-ENDLIST


  



  And the WebVTT file looks like this.

  



  WEBVTT  #Elemental Media Engine(TM) 2.16.0.602399
X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:191970

00:00:06.840 --> 00:00:10.320
once long ago in the deep blue below

00:00:12.360 --> 00:00:14.370
Don't be silly, Gran Mother

00:00:14.870 --> 00:00:16.700
Everybody knows there's no such thing as

00:00:16.700 --> 00:00:17.200
Mermaids

00:00:17.620 --> 00:00:21.570
You wouldn't say that if you has meet one. You've meet a Mermaid

00:00:24.250 --> 00:00:25.180
This just came in

00:00:25.480 --> 00:00:26.630
I wanted to take priority

00:00:27.180 --> 00:00:28.500
And we followed stories like this before

00:00:28.640 --> 00:00:31.620
Would witches working mummies. No not like this

00:00:31.630 --> 00:00:33.190
Hundreds of people are testifying

00:00:33.370 --> 00:00:34.600
Welcome to Mississippi

00:00:42.390 --> 00:00:47.270
There's a powerful magic in you the spirit of the ocean

00:00:47.690 --> 00:00:53.940
Let me introduce you to your dreams, The Little Mermaid, off the Mississippi

00:01:01.880 --> 00:01:03.580
She was so beautiful

00:01:04.040 --> 00:01:05.270
And I know she was real

00:01:07.850 --> 00:01:08.550
I'm skeptical

00:01:13.460 --> 00:01:14.410
You shouldn't be here

00:01:17.560 --> 00:01:24.130
Mermaids do not exist

00:01:31.420 --> 00:01:34.300
Look isn't it beautiful? Sorry I have to go.

00:01:35.340 --> 00:01:48.570
Elizabeth, How can this be? It's Lock he knows i'm here he summoned me.

00:01:48.570 --> 00:01:50.570
We have to save here.

00:02:03.570 --> 00:02:05.570
Here soul is mine

00:02:05.570 --> 00:02:06.570
Take it

00:02:10.570 --> 00:02:12.570
It's the only way

00:02:15.000 --> 00:02:17.570
I believe

00:02:23.000 --> 00:02:25.570
Mississippi has always been magic

00:02:36.000 --> 00:02:38.000
Elizabeth please


  



  I am trying to replicate this with FFMpeg. I have tried the following command.

  



  ffmpeg -i little-mermaid.mov -i little-mermaid.srt -c copy -c:s webvtt -start_number 0 -hls_time 10000 -f hls mermaid/Eng/master.m3u8


  



  This creates a WebVTT file but it is completely wrong and out of sync. See below.

  



  All the times have changed and it's removed the first two digits from each section.

  



  WEBVTT

00:06.882 --> 00:10.362
once long ago in the deep blue below

00:12.402 --> 00:14.412
Don't be silly, Gran Mother

00:14.912 --> 00:16.742
Everybody knows there's no such thing as

00:16.742 --> 00:17.242
Mermaids

00:00:17.620 -- 00:00:21.570
You wouldn't say that if you has meet one. You've meet a Mermaid

00:24.292 --> 00:25.222
This just came in

00:25.522 --> 00:26.672
I wanted to take priority

00:27.222 --> 00:28.542
And we followed stories like this before

00:28.682 --> 00:31.662
Would witches working mummies. No not like this

00:31.672 --> 00:33.232
Hundreds of people are testifying

00:33.412 --> 00:34.642
Welcome to Mississippi

00:42.432 --> 00:47.312
There's a powerful magic in you the spirit of the ocean

00:47.732 --> 00:53.982
Let me introduce you to your dreams, The Little Mermaid, off the Mississippi

01:01.922 --> 01:03.622
She was so beautiful

01:04.082 --> 01:05.312
And I know she was real

01:07.892 --> 01:08.592
I'm skeptical

01:13.502 --> 01:14.452
You shouldn't be here

01:17.602 --> 01:24.172
Mermaids do not exist

01:31.462 --> 01:34.342
Look isn't it beautiful? Sorry I have to go.

01:35.382 --> 01:48.612
Elizabeth, How can this be? It's Lock he knows i'm here he summoned me.

01:48.612 --> 01:50.612
We have to save here.

02:03.612 --> 02:05.612
Here soul is mine

02:05.612 --> 02:06.612
Take it

02:10.612 --> 02:12.612
It's the only way

02:15.042 --> 02:17.612
I believe

02:23.042 --> 02:25.612
Mississippi has always been magic

02:36.042 --> 02:38.042
Elizabeth please


  



  I am trying to decide if it just makes sense to convert the .srt to WebVTT and use that file without encoding with FFMPEG just create a .m3u8 file with -hls_flag single_file that points to it but not sure what implementation this might cause.

  



  Can anyone suggest how I could do this or where I might be going wrong ?

  



  Here is the video file I am using if anyone wants to run the FFMPEG command above to test.

  



  http://www.hd-trailers.net/movie/the-little-mermaid/

  



  Thanks

  


• Why Do Some of the Codecs in FFMPEG's Supported Codec List Show "encoders :" or "decoders :" in Parenthesis ?

  4 mai 2020, par spaceman

  If you open the Command Prompt, and run ffmpeg -codecs,
  
you will get a long list of Codecs that FFMPEG supports.

  



  Here's a small sample of the list :

  



   DEV.L. h261                 H.261
 DEV.L. h263                 H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2
 D.V.L. h263i                Intel H.263
 DEV.L. h263p                H.263+ / H.263-1998 / H.263 version 2
 DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (encoders: libx264 libx264rgb)
 D.V.LS hevc                 H.265 / HEVC


  



  Now If you briefly go over the whole list,
  
you see that most Codecs in this list appear with their Name and Description,
  
but some of the Codecs also include parenthesis in the Description, and in the parenthesis,
  
they specify "encoders :" or "decoders :".

  



  For example :

  



  1)

  



   DEV.LS h264                 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (encoders: libx264 libx264rgb)


  



  2)

  



   DEVILS jpeg2000             JPEG 2000 (decoders: jpeg2000 libopenjpeg) (encoders: jpeg2000 libopenjpeg)


  



  3)

  



   DEV.L. msmpeg4v3            MPEG-4 part 2 Microsoft variant version 3 (decoders: msmpeg4) (encoders: msmpeg4)


  



  4)

  



   DEA.L. aac                  AAC (Advanced Audio Coding) (encoders: aac libvo_aacenc)


  



  5)

  



   DEA.L. amr_nb               AMR-NB (Adaptive Multi-Rate NarrowBand) (decoders: amrnb libopencore_amrnb) (encoders: libopencore_amrnb)
 DEA.L. amr_wb               AMR-WB (Adaptive Multi-Rate WideBand) (decoders: amrwb libopencore_amrwb) (encoders: libvo_amrwbenc)


  



  My question :

  



  Why do some Codecs have those parenthesis, specifying Encoders/Decoders,
  
while other (in fact : most) codecs don't have these parenthesis ?

  


• ffmpeg creates an mp4 stream which results error in Firefox

  23 janvier 2020, par Daniel

  I’m about to play an fmp4 in HTML5 video element.

  I was successfully created a websocket to pass ffmpeg’s output into MSE.

  However when I try to open the page in Firefox (72.0.1, 64bit, under Ubuntu 18.04LTS), it always results an error :

  Media resource blob:http://localhost/XXXX could not be decoded, error: Error Code: NS_ERROR_FAILURE (0x80004005)
  
  Details: virtual mozilla::MediaResult mozilla::MP4ContainerParser::IsInitSegmentPresent(const mozilla::MediaSpan &): Invalid Top-Level Box:f"

  This is my FFMPEG’s line :

  ffmpeg -r 5 -i rtsp://IPCAMERA -c:v copy -an -movflags +frag_keyframe+empty_moov+default_base_moof -f mp4 pipe:1

  This is how the server side Java (with Tomcat engine) parses the output of this command (this might be inefficient but for now is ok) :

  ProcessBuilder b = new ProcessBuilder(FFMPEGCOMMAND.split("\\s+"));
  
  try {
  
      p = b.start();
  
  } catch (IOException e) {
  
      e.printStackTrace();
  
  }
  
  InputStream input = p.getInputStream();
  
  int bytes_read = 0;
  
  byte buffer[] = new byte[512];
  
  try {
  
      while (0 < (bytes_read = input.read(buffer, 0, 512))) {
  
          System.out.println("Bytes read:" + bytes_read);
  
          this.session.getBasicRemote().sendBinary(ByteBuffer.wrap(buffer));
  
      }
  
  } catch (IOException e) {
  
      e.printStackTrace();
  
  }

  Then the client side is a websocket-MSE like in this repo.

  Results :

  1. When I debug the server side, and there is a breakpoint before the sendBinary call, and I wait for some seconds before letting run the server side, then a first picture is shown in the browser, but then immediately goes onto the error above.

  2. If I run the server side (without any breakpoints), the browser does not show any picture, it immediately goes onto the error.

  Invalid Top-Level box error message is always followed by (a) random garbage character(s).

  The proof that this should be working is in the point 1. If I wait some time before letting roll the data to the client, it can decode 1 (or maybe more frames) before reaching that error.

  This might be an error with my ffmpeg command-line.

  However I could not really find any good resources on this topic (only found those ones which related to older releases of Firefox).

  Update1

  Here is the FFMPEG log when the same command creates an mp4 file instead of the pipe : https://pastebin.com/Gjq2vxeT

  Here is the detailed Firefox log with the wrong box :

  Details: virtual mozilla::MediaResult mozilla::MP4ContainerParser::IsInitSegmentPresent(const mozilla::MediaSpan &): Invalid Top-Level Box:f

  Please note, Top-Level Box is always ’f’ when I’m doing the scenario marked in point 2 (running without breakpoints).

  Update2 :

  Here are the ffmpeg’s current output (with numeric and alphanumeric representation, for the first 128 items) : https://pastebin.com/DeJMfNYs

  The interesting thing is that the first 4 bytes seems invalid for me. However starting from byte4 (5th byte), it seems OK ("ftyp").

  Could you please confirm this ?