Audio out of sync after downloaded MPEG dash video

[kfiroflwp]

Hello!

I have downloaded all the segments of a MPD and converted to MP4. Content of the MPD:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<MPD id="xxxxxxxxxxxx" profiles="urn:mpeg:dash:profile:isoff-main:2011" type="static" availabilityStartTime="2017-05-09T18:33:14.000Z" publishTime="2017-05-09T18:33:28.000Z" mediaPresentationDuration="P0Y0M0DT1H32M55.442S" minBufferTime="P0Y0M0DT0H0M1.000S" bitmovin:version="1.7.0" xmlns:ns2="http://www.w3.org/1999/xlink" xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:bitmovin="http://www.bitmovin.net/mpd/2015">
    <Period>
        <AdaptationSet mimeType="video/mp4">
            <SegmentTemplate media="../video/$RepresentationID$/cenc_dash/segment_$Number$.m4s" initialization="../video/$RepresentationID$/cenc_dash/init.mp4" duration="4004" startNumber="0" timescale="1000"/>
            <Representation id="938_3072000" bandwidth="3072000" width="1280" height="938" frameRate="30" codecs="avc1.4D0028">
                <ContentProtection schemeIdUri="urn:mpeg:dash:mp4protection:2011" value="cenc" cenc:default_KID="xxxxxxxxxxxxxxxxxxx2" xmlns:cenc="urn:mpeg:cenc:2013"/>
                <ContentProtection schemeIdUri="urn:uuid:xxxxxxxxxxxxxxxxxxx3">
                    <cenc:pssh xmlns:cenc="urn:mpeg:cenc:2013">xxxxxxxxxxxxxxxxxxx</cenc:pssh>
                </ContentProtection>
            </Representation>
            <Representation id="938_2406400" bandwidth="2406400" width="1280" height="938" frameRate="30" codecs="avc1.4D0028">
                <ContentProtection schemeIdUri="urn:mpeg:dash:mp4protection:2011" value="cenc" cenc:default_KID="xxxxxxxxxxxxxxxxxxx2" xmlns:cenc="urn:mpeg:cenc:2013"/>
                <ContentProtection schemeIdUri="urn:uuid:xxxxxxxxxxxxxxxxxxx3">
                    <cenc:pssh xmlns:cenc="urn:mpeg:cenc:2013">xxxxxxxxxxxxxxxxxxx</cenc:pssh>
                </ContentProtection>
            </Representation>
            <Representation id="404_1792000" bandwidth="1792000" width="720" height="404" frameRate="30" codecs="avc1.4D001E">
                <ContentProtection schemeIdUri="urn:mpeg:dash:mp4protection:2011" value="cenc" cenc:default_KID="xxxxxxxxxxxxxxxxxxx2" xmlns:cenc="urn:mpeg:cenc:2013"/>
                <ContentProtection schemeIdUri="urn:uuid:xxxxxxxxxxxxxxxxxxx3">
                    <cenc:pssh xmlns:cenc="urn:mpeg:cenc:2013">xxxxxxxxxxxxxxxxxxx</cenc:pssh>
                </ContentProtection>
            </Representation>
        </AdaptationSet>
        <AdaptationSet lang="es" mimeType="audio/mp4" codecs="mp4a.40.2" bitmovin:label="Lang 1">
            <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
            <SegmentTemplate media="../audio/$RepresentationID$/cenc_dash/segment_$Number$.m4s" initialization="../audio/$RepresentationID$/cenc_dash/init.mp4" duration="4000" startNumber="0" timescale="1000"/>
            <Representation id="2_stereo_128000" bandwidth="128000" audioSamplingRate="48000">
                <ContentProtection schemeIdUri="urn:mpeg:dash:mp4protection:2011" value="cenc" cenc:default_KID="xxxxxxxxxxxxxxxxxxx2" xmlns:cenc="urn:mpeg:cenc:2013"/>
                <ContentProtection schemeIdUri="urn:uuid:xxxxxxxxxxxxxxxxxxx3">
                    <cenc:pssh xmlns:cenc="urn:mpeg:cenc:2013">xxxxxxxxxxxxxxxxxxx</cenc:pssh>
                </ContentProtection>
            </Representation>
        </AdaptationSet>
        <AdaptationSet lang="en" mimeType="audio/mp4" codecs="mp4a.40.2" bitmovin:label="Lang 2">
            <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
            <SegmentTemplate media="../audio/$RepresentationID$/cenc_dash/segment_$Number$.m4s" initialization="../audio/$RepresentationID$/cenc_dash/init.mp4" duration="4000" startNumber="0" timescale="1000"/>
            <Representation id="1_stereo_128000" bandwidth="128000" audioSamplingRate="48000">
                <ContentProtection schemeIdUri="urn:mpeg:dash:mp4protection:2011" value="cenc" cenc:default_KID="xxxxxxxxxxxxxxxxxxx2" xmlns:cenc="urn:mpeg:cenc:2013"/>
                <ContentProtection schemeIdUri="urn:uuid:xxxxxxxxxxxxxxxxxxx3">
                    <cenc:pssh xmlns:cenc="urn:mpeg:cenc:2013">xxxxxxxxxxxxxxxxxxx</cenc:pssh>
                </ContentProtection>
            </Representation>
        </AdaptationSet>
    </Period>
</MPD>

I have checked with the "Network" tab of the browser the segment numbers. Then when I want to join video and audio, the audio is slightly out of sync. The duration of each audio segment changes between 00:00:03.99 and 00:00:04.01 if it is odd or even, while all the video segments are 00:00:04.01

The total video duration number is not correct either, since in the player it appears as 01:32.55 and with the ffmpeg the "muxed" video returns 01:32:56.83

When I downloaded and converted it didn't throw me any errors.

Here the commands I used (list.txt contains: file 'segment0.mp4', 'segment1.mp4', etc):

ffmpeg -f concat -safe 0 -i list.txt -c copy video.mp4
ffmpeg -f concat -safe 0 -i list.txt -c copy audio.m4a

ffmpeg -i audio.m4a -i video.mp4 -c copy muxed.mp4

Could someone help?

Thanks in advance!

[ProWo]

Play your mp4 with VLC player, Tool menu, track synchronization, change the audio track synch value while playing, until the synch is ok. Then go to a later point in your video. Synch still ok?
Then this is a constant audio/video delay, which you can easily correct by remuxing the video and entering the found A/V delay in the audio track.

[kfiroflwp]

Play your mp4 with VLC player, Tool menu, track synchronization, change the audio track synch value while playing, until the synch is ok. Then go to a later point in your video. Synch still ok?
Then this is a constant audio/video delay, which you can easily correct by remuxing the video and entering the found A/V delay in the audio track.

Hi! I tried but it's still out of sync

[davexnet]

Perhaps Avisynth AlignedSplice