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• Why is the FindClass/JNI function behaving differently on nexus 5 and Honor Play ?

  17 août 2020, par Owl

  MobileFFmpeg v4.3.1LTS works on Honor Play, but doesn't work on Nexus 5. Why ?

  


  The build for Honor Play and nexus 5 is the same ->armeabi-v7a

  


  


  https://github.com/tanersener/mobile-ffmpeg/releases/tag/v4.3.1.LTS

  


  Nexus5 :enter image description here

  


  HonorPlay :enter image description here

  


  


  


  NDK = ndk-r14b

  


  


  


  JDK = jdk1.8.0_77

  


  


  I will ask the question immediately in English stackoverflow. Developing a game in Unreal Engine 4 v24.3. In the code itself there are only 2 lines that relate to MobileFFmpeg :

  


  Enabling the function :

  


  extern "C"
{
    int ffmpeg_execute(int argc, char** argv);
}


  


  Calling a function with ffmpeg parameters

  


  ffmpeg_execute(arg.size(), arg.data());


  


  Without mobile FFmpeg, the app on nexus 5 starts and works stably. When I start with FFmpeg, an error immediately appears and the app crashes :

  


  enter image description here

  


  The FindClass function does not work, the call itself is declared in mobile ffmpeg.c :

  


  /** Full name of the Config class */
const char *configClassName = "com/arthenica/mobileffmpeg/Config";


  


  ...

  


  /**
 * Called when 'mobileffmpeg' native library is loaded.
 *
 * @param vm pointer to the running virtual machine
 * @param reserved reserved
 * @return JNI version needed by 'mobileffmpeg' library
 */
jint JNI_OnLoad(JavaVM *vm, void *reserved) {
    JNIEnv *env;
    if ((*vm)->GetEnv(vm, (void**)(&env), JNI_VERSION_1_6) != JNI_OK) {
        LOGE("OnLoad failed to GetEnv for class %s.\n", configClassName);
        return JNI_FALSE;
    }

    jclass localConfigClass = (*env)->FindClass(env, configClassName);
    if (localConfigClass == NULL) {
        LOGE("OnLoad failed to FindClass %s.\n", configClassName);
        return JNI_FALSE;
    }
...


  


  I can't see what the FindClass(C++) function returns, Android Studio doesn't want to stop on the JNI_OnLoad(C++) function during debug.

  


  What are the assumptions why FindClass behavior is different on two phones ?

  


• ffmpeg burned-in subtitles render in the wrong font

  21 août 2024, par dv151

  Trying to burn in subtitles to a video in FFMPEG in GothamProBold font. No matter what I do it keeps reverting to Helvetica. From the console, I see that FFMPEG seems to load the font without error. Then switches over to font provider "coretext"

  


  [Parsed_subtitles_0 @ 0x7fed054048c0] Loading font file '/Projects/Fonts/GothaProBol.otf'
[Parsed_subtitles_0 @ 0x7fed054048c0] Using font provider coretext
[Parsed_subtitles_0 @ 0x7fed054048c0] fontselect: (GothaProBol.otf, 400, 0) -> /System/Library/Fonts/Helvetica.ttc, -1, Helvetica


  


  It seems like it has my font loaded, then loads what is likely a system default of Helvetica instead. My guess is that my chosen font isn't actually loading after all.

  


  FFMPEG command (called from python) is as follows :

  


  ffmpeg_cmd = ["ffmpeg", 
              "-i", self.source_video_uri, 
              "-y",
              "-c:v", "prores", "-profile:v", "1", 
              "-c:a", "pcm_s16be", 
              "-vf", f"subtitles={srt_uri}:fontsdir=/Projects/Fonts:force_style='Fontname=GothaProBol.otf'",
              f"{self.source_video_uri}_render.mov"]

subprocess.call(ffmpeg_cmd)


  


  Any ideas ?

  


  UPDATE : Found this setting in libass header file "ass.h" - which ffmpeg calls when using the subtitle filter. Don't know how to actually set this variable when ffmpeg calls libass, but here it is. Line 182 :

  


   * \brief Default Font provider to load fonts in libass' database
 *
 * NONE don't use any default font provider for font lookup
 * AUTODETECT use the first available font provider
 * CORETEXT force a CoreText based font provider (OS X only)
 * FONTCONFIG force a Fontconfig based font provider
 *
 * libass uses the best shaper available by default.
 */
typedef enum {
    ASS_FONTPROVIDER_NONE       = 0,
    ASS_FONTPROVIDER_AUTODETECT = 1,
    ASS_FONTPROVIDER_CORETEXT,
    ASS_FONTPROVIDER_FONTCONFIG,
    ASS_FONTPROVIDER_DIRECTWRITE,
} ASS_DefaultFontProvider;


  


  RE : ANSWER BELOW : For the most part, it seems that if your font is installed in /System/Fonts or /Library/Fonts then CoreText can find it. Though in some cases, the naming conventions can be quite particular and non-intuitive. It also can't seem to find all fonts, necessarily.

  


  For example : Gotham Pro Bold, in the /Library/Fonts folder on my system, file named "GothaProBol.otf" is correctly passed to fontname as : GothamPro-Bold or just Gotham Pro. Gotham Pro Bold, GothamPro, Gotham Pro-Bold, GothaProBol, and GothaProBol.otf do NOT work.

  


  For most fonts it seems the preferred convention is FontName-Style/Weight as displayed in Mac OS's FontBook, not the filename.

  


  That said, I have a novelty 'Game of Thrones.ttf' font in the same folder as Gotham Pro, and I can't get CoreText to connect to it under any of the above naming conventions.

  


• Python and ffmpeg audio sync and screen recording issues

  9 août 2020, par odddollar

  I'm using ffmpeg and python to record my desktop screen. When the program is run, it starts recording, then when I press a key-combo it cuts off the last x amount of seconds and saves it then starts recording again ; similar to the "record that" functionality of windows game bar.

  


  I have it working so it records video just fine, but then I change the ffmpeg command to record audio from my desktop and I get an error saying ValueError: could not convert string to float: 'N/A' occurring when I try to calculate the length of the recorded video. It appears as though the recording isn't being stopped until after I try to calculate the video length, even though this exact same code works fine when not recording audio.

  


  Additionally, I also have an issue when recording audio in that the audio is a couple hundred milliseconds in front of the video. It's not a lot but it's enough to be noticeable.

  


  What I'm overall asking, is there a way I can modify the ffmpeg command to prevent the audio desync issues, and what might be causing the problems I'm getting when attempting to find the length of the video with audio ?

  


  import keyboard, signal
from os import remove
from os.path import isfile
from subprocess import Popen, getoutput
from datetime import datetime
import configparser

class Main:
    def __init__(self, save_location, framerate, duration):
        self.save_location = save_location
        self.framerate = int(framerate)
        self.duration = int(duration)
        self.working = self.save_location + '\\' + 'working.avi'
        self.start_recording()

    def start_recording(self):
        if isfile(self.working):
            remove(self.working)

        # start recording to working file at set framerate
        self.process = Popen(f'ffmpeg -thread_queue_size 578 -f gdigrab -video_size 1920x1080 -i desktop -f dshow -i audio="Stereo Mix (Realtek High Definition Audio)" -b:v 7M -minrate 4M -framerate {self.framerate} {self.working}')
        #self.process = Popen(f'ffmpeg -f gdigrab -framerate {self.framerate} -video_size 1920x1080 -i desktop -b:v 7M -minrate 2M {self.working}')

    def trim_video(self):
        # stop recording working file
        self.process.send_signal(signal.CTRL_C_EVENT)

        # call 'cause I have to
        getoutput(f"ffprobe -i {self.working}")

        # get length of working video
        length = getoutput(f'ffprobe -i {self.working} -show_entries format=duration -v quiet -of csv="p=0"')

        # get time before desired recording time
        start = float(length) - self.duration

        # get save location and title
        title = self.save_location+'\\'+self.get_time()+'.avi'

        # cut to last amount of desired time
        Popen(f"ffmpeg -ss {start} -i {self.working} -c copy -t {self.duration} {title}")
        getoutput(f"ffprobe -i {self.working}")

        self.start_recording()

    def get_time(self):
        now = datetime.now()
        return now.strftime("%Y_%m_%d#%H-%M-%S")


if __name__ == "__main__":
    config = configparser.ConfigParser()
    config.read("settings.ini")
    config = config["DEFAULT"]

    run = Main(config["savelocation"].replace("\\", "\\\\"), config["framerate"], config["recordlast"])
    keyboard.add_hotkey("ctrl+shift+alt+g", lambda:run.trim_video())

    while True:
        try:
            keyboard.wait()
        except KeyboardInterrupt:
            pass


  


  The contents of the settings.ini file are listed below

  


  [DEFAULT]
savelocation = C:\
framerate = 30
recordlast = 10


  


  In the code block, the first line with self.process = Popen is the one that records audio and has the issues, the second line (the commented out one below) is the one that works fine.