If I attach the audioconvert filter like this, the export works:

    playlist.attach(mlt.Filter(profile, "audioconvert"))

When loading the xml, this filter seems to be attached automatically, along 
with avcolor_space. But it is not set for the playlist that I create.

Should I wrap my playlist in something so that the loader can do its thing? Or 
should I add these filters manually?

/Rickard

On Thu, Jul 20, 2023, at 22:19, Rickard Lindberg wrote:
> I tried to generate an XML file using the "xml" consumer and got this:
> 
> <?xml version="1.0"?>
> <mlt LC_NUMERIC="C" version="6.26.1" producer="playlist0">
>   <profile description="DV/DVD PAL" width="720" height="576" progressive="0" 
> sample_aspect_num="16" sample_aspect_den="15" display_aspect_num="4" 
> display_aspect_den="3" frame_rate_num="25" frame_rate_den="1" 
> colorspace="601"/>
>   <producer id="producer0" in="0" out="14999">
>     <property name="length">15000</property>
>     <property name="eof">pause</property>
>     <property name="resource">red</property>
>     <property name="aspect_ratio">1.06667</property>
>     <property name="mlt_service">color</property>
>   </producer>
>   <producer id="producer1" in="0" out="14999">
>     <property name="length">15000</property>
>     <property name="eof">pause</property>
>     <property name="resource">green</property>
>     <property name="aspect_ratio">1.06667</property>
>     <property name="mlt_service">color</property>
>   </producer>
>   <playlist id="playlist0">
>     <entry producer="producer0" in="0" out="25"/>
>     <blank length="26"/>
>     <entry producer="producer1" in="0" out="25"/>
>   </playlist>
> </mlt>
> 
> Melt seems to be able to render this just fine using
> 
> mlt-melt test.xml -consumer avformat target=export.mp4 acodec=aac
> 
> So my guess is that I need to do something different in my code. Question is 
> what...
> 
> /Rickard
> 
> On Thu, Jul 20, 2023, at 22:16, Brian Matherly wrote:
>> 
>> Your MLT is over 2 years old. Can you try with a newer version?
>> 
>> Also, it would be helpful to reproduce with a melt command so that others 
>> can easily recreate the problem.
>> 
>> ~Brian
>> 
>> 
>> On Thursday, July 20, 2023 at 03:00:45 PM CDT, Rickard Lindberg 
>> <rick...@rickardlindberg.me> wrote:
>> 
>> 
>> Hi,
>> 
>> I'm having trouble exporting a playlist that contains blanks. Here is a small
>> program to reproduce the problem:
>> 
>>     mlt.Factory().init()
>>     profile = mlt.Profile()
>>     playlist = mlt.Playlist()
>>     playlist.append(mlt.Producer(profile, "color:red"), 0, 25)
>>     playlist.blank(25)
>>     playlist.append(mlt.Producer(profile, "color:green"), 0, 25)
>>     consumer = mlt.Consumer(profile, "avformat")
>>     consumer.set("target", "export.mp4")
>>     consumer.connect(playlist)
>>     consumer.start()
>>     while consumer.is_stopped() == 0:
>>         time.sleep(1)
>> 
>> The output:
>> 
>>     [libx264 @ 0x7f61740023c0] interlace + weightp is not implemented
>>     [mp4 @ 0x7f6174000f40] Using AVStream.codec to pass codec parameters to 
>> muxers is deprecated, use AVStream.codecpar instead.
>>     [mp4 @ 0x7f6174000f40] Using AVStream.codec to pass codec parameters to 
>> muxers is deprecated, use AVStream.codecpar instead.
>>     [aac @ 0x7f6174004e40] Input contains (near) NaN/+-Inf
>>     [consumer avformat] error with audio encode: -22 (frame 28)
>>     [aac @ 0x7f6174004e40] Input contains (near) NaN/+-Inf
>>     [consumer avformat] error with audio encode: -22 (frame 28)
>>     [aac @ 0x7f6174004e40] Input contains (near) NaN/+-Inf
>>     [consumer avformat] error with audio encode: -22 (frame 29)
>>     [aac @ 0x7f6174004e40] 5 frames left in the queue on closing
>> 
>> Without
>> 
>>     playlist.blank(25)
>> 
>> the export works fine.
>> 
>> I assumed that if no producer exist to produce sound, silence will be used. 
>> Is
>> that assumption wrong? Do I need to insert a producer for silence? Or is this
>> an issue with the aac encoder?
>> 
>> Versions:
>> 
>>     mlt: 6.26.1
>>     ffmpeg: 4.4.1
>> 
>> /Rickard
>> 
>> _______________________________________________
>> Mlt-devel mailing list
>> Mlt-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/mlt-devel
> 
> 
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