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• Using ffmpeg dll's from a windows 32 bit app

  8 avril 2020, par Derek

  I am trying to use ffmpeg via dll calls from a win32 app (compiled in clarion)

  



  I transcoded the example file encode_video.c and that worked 100% however I was left with a .h264 file instead of a .mp4 file.

  



  I then transcoded the example muxing.c however it crashes and I am at a loss for options.

  



  Any help would be most appreciated.

  



  Encode_mp4 ROUTINE
! avformat_alloc_output_context2 *******************************************************************************************
file_name = 'myvideo.mp4'
! Try guess format from filename
if CHECK_STACK then ds_SaveStack .
Result = avformat_alloc_output_context2(ThisPtrPtr, 0, NullCString, file_name);
if CHECK_STACK then ds_TestStack .
if Result < 0
    ds_OutputDebugString('avformat_alloc_output_context2 Try guess format failed, try mpeg', TRUE)
    CString1 = 'mpeg'
    if CHECK_STACK then ds_SaveStack .
    Result = avformat_alloc_output_context2(ThisPtrPtr, 0, CString1, file_name);
    if CHECK_STACK then ds_TestStack .
    if Result < 0
        ds_OutputDebugString('avformat_alloc_output_context2 failed', TRUE)
        stop('Could not allocate output format context')
        exit
    end
end
formater_ctxt &= (ThisPtrPtr)
!ds_OutputDebugString('formater_ctxt=' & address(formater_ctxt), TRUE)
assert(not(formater_ctxt &= NULL), 'Check AVFormatContext formater_ctxt')
do VerifyFormatContext
assert(formater_ctxt.oformat > 0, 'Check AVFormatContext formater_ctxt.oformat')
formater &= (formater_ctxt.oformat)
do VerifyFormat
ds_OutputDebugString('avformat_alloc_output_context2 OK', TRUE)

! avcodec_find_encoder *******************************************************************************************
if CHECK_STACK then ds_SaveStack .
encoder &= avcodec_find_encoder(formater.video_codec)
if CHECK_STACK then ds_TestStack .
if encoder &= NULL
    ds_OutputDebugString('avcodec_find_encoder failed', TRUE)
    stop('Could not find encoder')
    exit
end
do VerifyEncoder
ds_OutputDebugString('avcodec_find_encoder OK', TRUE)

! avformat_new_stream *******************************************************************************************
if CHECK_STACK then ds_SaveStack .
stream &= avformat_new_stream(formater_ctxt, encoder)
if CHECK_STACK then ds_TestStack .
if stream &= NULL 
    ds_OutputDebugString('avformat_new_stream failed', TRUE)
    stop('Could not create new stream')
    exit
end
do VerifyStream
stream.id = formater_ctxt.nb_streams-1
ds_OutputDebugString('avformat_new_stream OK', TRUE)

! avcodec_alloc_context3 *******************************************************************************************
if CHECK_STACK then ds_SaveStack .
encoder_ctxt &= avcodec_alloc_context3(encoder)
if CHECK_STACK then ds_TestStack .
if encoder_ctxt &= NULL 
    ds_OutputDebugString('avcodec_alloc_context3 failed', TRUE)
    stop('Could not allocate video codec context')
    exit
end
do VerifyEncoderContext
ds_OutputDebugString('avcodec_alloc_context3 OK', TRUE)

! Video settings *******************************************************************************************
do InitVideoSettings

assert(AV_CODEC_FLAG_GLOBAL_HEADER = bshift(1, 22), 'Check AV_CODEC_FLAG_GLOBAL_HEADER')
if band(formater.flags, AVFMT_GLOBALHEADER)
   encoder_ctxt.flags = bor(encoder_ctxt.flags, AV_CODEC_FLAG_GLOBAL_HEADER) !avctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
end

! avcodec_open2 *******************************************************************************************
if CHECK_STACK then ds_SaveStack .
Result = avcodec_open2(encoder_ctxt, encoder, 0)
if CHECK_STACK then ds_TestStack .
if Result < 0
    ds_OutputDebugString('avcodec_open2 failed.  Result=' & Result, TRUE)
    stop('Could not open codec')
    exit
end
ds_OutputDebugString('avcodec_open2 OK', TRUE)

! av_frame_alloc *******************************************************************************************
if CHECK_STACK then ds_SaveStack .
frame &= av_frame_alloc();
if CHECK_STACK then ds_TestStack .
if frame &= NULL
    ds_OutputDebugString('av_frame_alloc failed', TRUE)
    stop('Could not allocate video frame')
    exit
end
do VerifyFrame
frame.format = encoder_ctxt.pix_fmt
frame.width = encoder_ctxt.width
frame.height = encoder_ctxt.height
ds_OutputDebugString('av_frame_alloc OK', TRUE)

! av_frame_get_buffer *******************************************************************************************
if CHECK_STACK then ds_SaveStack .
Result = av_frame_get_buffer(frame, 32)
if CHECK_STACK then ds_TestStack .
if Result < 0
    ds_OutputDebugString('av_frame_get_buffer failed', TRUE)
    stop('Could not allocate video frame buffer Error = ' & Result)
    exit
end
do VerifyFrameBuffer
ds_OutputDebugString('av_frame_get_buffer OK', TRUE)

!frame->data offset=0  Array[8] of *int8_t
UseData0 &= (frame.data[1])
UseData1 &= (frame.data[2])
UseData2 &= (frame.data[3])

if CHECK_STACK then ds_SaveStack .
Result = avcodec_parameters_from_context(stream.codecpar, encoder_ctxt);
if CHECK_STACK then ds_TestStack .
if Result < 0
    ds_OutputDebugString('avcodec_parameters_from_context failed', TRUE)
    stop('Could not initialize stream parameters')
    exit
end
ds_OutputDebugString('avcodec_parameters_from_context OK', TRUE)

! av_dump_format *******************************************************************************************
ds_OutputDebugString('before call to av_dump_format  file_name=' & file_name, TRUE)
av_dump_format(formater_ctxt, 0, file_name, 1)


  



  I get a crash at last line - call to av_dump_format()

  



  If I comment this code then I get a crash on the very next lib call :

  



      ! avio_open *******************************************************************************************
if not(band(formater.flags, AVFMT_NOFILE)) 
    ds_OutputDebugString('before call to avio_open  file_name=' & file_name, TRUE)
    ThisInt &= address(formater_ctxt.pb)
    Result = avio_open(ThisInt, file_name, AVIO_FLAG_WRITE)


  



  Strangely if I comment the setup call to av_log_set_callback(my_log_callback) then the crash moves down to the next lib call : avformat_write_header

  


• OpenCV VideoWriter produces "can't find starting number" error

  5 avril 2020, par user3325139

  I am trying to write 16-bit grayscale video using the FFV1 codec and opencv.ImageWriter on Windows 10

  



  Here is my code :

  



  import numpy as np
import cv2, pdb

print(cv2.getBuildInformation())

def to8(img):
    return (img/256).astype('uint8')

cap = cv2.VideoCapture(0+cv2.CAP_DSHOW)
cap.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter_fourcc('Y','1','6',' '))
cap.set(cv2.CAP_PROP_CONVERT_RGB, False)

out = cv2.VideoWriter('out.avi', cv2.VideoWriter_fourcc('F','F','V','1'), cap.get(cv2.CAP_PROP_FPS), (int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)),int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))))

while True:
    ret, frame = cap.read()
    frame = cv2.normalize(frame,None,0,65535,cv2.NORM_MINMAX)

    cv2.imshow('Video',to8(frame))
    out.write(frame)

    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
cap.release()
out.release()
cv2.destroyAllWindows()


  



  And here is my error :

  



  [ERROR:0] global C:\projects\opencv-python\opencv\modules\videoio\src\cap.cpp (415) cv::VideoWriter::open VIDEOIO(CV_IMAGES): raised OpenCV exception:

OpenCV(4.2.0) C:\projects\opencv-python\opencv\modules\videoio\src\cap_images.cpp:253: error: (-5:Bad argument) CAP_IMAGES: can't find starting number (in the name of file): out.avi in function 'cv::icvExtractPattern'


  



  I am running this script from a command window with admin privileges. I've tried both making sure the output file does and does not exist before running.

  



  My OpenCV build information is here : https://pastebin.com/whtF6ixG

  



  Thanks !

  



  EDIT :
Based on Rotem's suggestion, instead of using VideoWriter I piped directly to FFMPEG using ffmpeg-python :

  



  import numpy as np
import cv2, pdb
import ffmpeg

def to8(img):
    return (img/256).astype('uint8')

cap = cv2.VideoCapture(0+cv2.CAP_DSHOW)
cap.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter_fourcc('Y','1','6',' '))
cap.set(cv2.CAP_PROP_CONVERT_RGB, False)

ff_proc = (
    ffmpeg
    .input('pipe:',format='rawvideo',pix_fmt='gray16le',s='%sx%s'%(int(cap.get(cv2.CAP_PROP_FRAME_WIDTH)),int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))),r='60')
    .output('out3.avi',vcodec='ffv1',an=None)
    .run_async(pipe_stdin=True)
)

while True:
    ret, frame = cap.read()

    cv2.imshow('Video',to8(frame))
    ff_proc.stdin.write(frame)

    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

out.terminate()
cap.release()
cv2.destroyAllWindows()


  


• Why won't this encrypted HLS video play on iOS (but works on Windows Chrome via hls.js library) ?

  8 mai 2023, par Ryan

  I am trying to play an MP4 test video.

  


  My /home/vagrant/Code/example/public/hls_hls.keyInfo is :

  


  https://example.com/hls.key
/home/vagrant/Code/example/public/hls_hls.key
467216aae8a26fb699080812628031955e304a66e9e4480f9b70d31d8fe94e9a


  


  My /home/vagrant/Code/example/public/hls_hls.key was generated using PHP : hex2bin('467216aae8a26fb699080812628031955e304a66e9e4480f9b70d31d8fe94e9a')

  


  The ffmpeg command for encrypting the video as HLS playlist with "ts" files :

  


  '/usr/bin/ffmpeg' '-y' '-i' 'storage/app/sample_media2/2020-02-27/Sample_Videos_5.mp4' 
'-c:v' 'libx264' '-s:v' '1920x1080' '-crf' '20' '-sc_threshold' '0' '-g' '48' 
'-keyint_min' '48' '-hls_list_size' '0' 
'-hls_time' '10' '-hls_allow_cache' '0' '-b:v' '4889k' '-maxrate' '5866k' 
'-hls_segment_type' 'mpegts' '-hls_fmp4_init_filename' 'output_init.mp4' 
'-hls_segment_filename' 'storage/app/public/test/output_1080p_%04d.ts' 
'-hls_key_info_file' '/home/vagrant/Code/example/public/hls_hls.keyInfo' 
'-strict' '-2' '-threads' '12' 'storage/app/public/test/output_1080p.m3u8'


  


  Then, I know from https://caniuse.com/#search=hls that Windows Chrome won't be able to play the HLS video without a library, so I use https://github.com/video-dev/hls.js/, and Windows Chrome successfully plays the encrypted video !

  


  However, iOS Safari is unable to play it (with or without the hls.js library).

  


  On iOS Safari, when I try to play the video, I see just a quick glimpse (less than a second) where the screen shows 0:15, so it must be reading and decrypting enough to know the correct duration of the video.

  


  So, to debug, I log events :

  


  const nativeHlsEvents = ['play', 'playing', 'abort', 'error', 'canplaythrough', 'waiting', 'loadeddata', 'loadstart', 'progress', 'timeupdate', 'volumechange'];
$.each(nativeHlsEvents, function (i, eventType) {
    video.addEventListener(eventType, (event) => {//https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement
        console.log(eventType, event);
        if (eventType === 'error') {
            console.error(video.error);//https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/error
        }
    });
});


  


  I see in the console log :

  


  loadstart, {"isTrusted":true}
progress, {"isTrusted":true}
play, {"isTrusted":true}
waiting, {"isTrusted":true}
error, {"isTrusted":true}
video.error, {}


  


  I don't know how to find more details about the error.

  


  Note that even though Windows Chrome successfully plays the video, it too shows warnings in the console log :

  


  {"type":"mediaError","details":"fragParsingError","fatal":false,"reason":"TS packet did not start with 0x47","frag":{"...
{"type":"mediaError","details":"fragParsingError","fatal":false,"reason":"no audio/video samples found","frag":{...


  


  Where is my problem ?