purple-gowhatsapp/send_file_checks.go at whatsmeow · hoehermann/purple-gowhatsapp · GitHub

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package main

import (
	"fmt"
	"github.com/alfg/mp4"
)

func check_mp4(data []byte) error {
	mp4, err := mp4.OpenFromBytes(data)
	if err != nil {
		return fmt.Errorf("An mp4 video file was provided, but it could not be analyzed: %v.", err)
	}
	if mp4 == nil {
		return fmt.Errorf("An mp4 video file was provided, but it could not be analyzed.")
	}
	// NOTE: WhatsApp seems to prefer MajorBrand == "mp42", MinorVersion == 0
	// TODO: also consider CompatibleBrands
	// TODO: check moov atom (faststart) location
	if mp4.Ftyp != nil && (mp4.Ftyp.MajorBrand == "mp42" || mp4.Ftyp.MajorBrand == "isom") && mp4.Moov != nil && mp4.Moov.IsFragmented == false {
		// NOTE: I assume video track must be at 0
		// presence of Avc1 box (Box.Name "avc1") indicates h264
		// see https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/QTFFChap3/qtff3.html
		// TODO: access h264 stream and check for yuv420
		video_ok := false
		audio_ok := true // TODO: actually check audio
		if len(mp4.Moov.Traks) == 1 || len(mp4.Moov.Traks) == 2 {
			trak := mp4.Moov.Traks[0]
			video_ok = trak.Mdia.Minf.Stbl != nil && trak.Mdia.Minf.Stbl.Stsd.Avc1 != nil
		}
		if video_ok && audio_ok {
			return nil
		} else {
			return fmt.Errorf("An mp42 video file was provided, but it has not the correct format. First track avc1 (aka. h264) video: %v Second track mp4a (aka. aac) audio (optional): %v", video_ok, audio_ok)
		}
	} else {
		return fmt.Errorf("An mp4 video file was provided, but it has not the correct container. Need brand: mp42, version: 0, fragmented: false.")
	}
	/*
	   handler.log.Infof("mp4: %+v", mp4)
	   handler.log.Infof("mp4.Ftyp: %+v", mp4.Ftyp)
	   handler.log.Infof("mp4.Moov: %+v", mp4.Moov)
	   handler.log.Infof("mp4.Moov.Mvhd: %+v", mp4.Moov.Mvhd)
	   for i, trak := range mp4.Moov.Traks {
	       handler.log.Infof("trak[%d]: %+v", i, trak)
	       handler.log.Infof("trak[%d].Tkhd: %+v", i, trak.Tkhd)
	       handler.log.Infof("trak[%d].Mdia: %+v", i, trak.Mdia)
	       handler.log.Infof("trak[%d].Mdia.Hdlr: %+v", i, trak.Mdia.Hdlr) // Handler:"vide", Handler:"soun"
	       handler.log.Infof("trak[%d].Mdia.Mdhd: %+v", i, trak.Mdia.Mdhd)
	       handler.log.Infof("trak[%d].Mdia.Minf: %+v", i, trak.Mdia.Minf)
	       if trak.Mdia.Minf.Vmhd != nil {
	           handler.log.Infof("trak[%d].Mdia.Minf.Vmhd: %+v", i, trak.Mdia.Minf.Vmhd)
	       }
	       if trak.Mdia.Minf.Hmhd != nil {
	           handler.log.Infof("trak[%d].Mdia.Minf.Hmhd: %+v", i, trak.Mdia.Minf.Hmhd)
	       }
	       if trak.Mdia.Minf.Stbl != nil {
	           handler.log.Infof("trak[%d].Mdia.Minf.Stbl: %+v", i, trak.Mdia.Minf.Stbl)
	           handler.log.Infof("trak[%d].Mdia.Minf.Stbl.Stts: %+v", i, trak.Mdia.Minf.Stbl.Stts)
	           handler.log.Infof("trak[%d].Mdia.Minf.Stbl.Stsd: %+v", i, trak.Mdia.Minf.Stbl.Stsd)
	           if trak.Mdia.Minf.Stbl.Stsd.Avc1 != nil {
	               handler.log.Infof("trak[%d].Mdia.Minf.Stbl.Stsd.Avc1: %+v", i, trak.Mdia.Minf.Stbl.Stsd.Avc1)
	               handler.log.Infof("trak[%d].Mdia.Minf.Stbl.Stsd.Avc1.Box: %+v", i, trak.Mdia.Minf.Stbl.Stsd.Avc1.Box)
	           }
	       }
	   }
	*/
}