[FFmpeg-devel] [PATCH] Parsing ALS object type in MPEG-4

[Alex Converse]

On Tue, Nov 10, 2009 at 4:29 PM, Baptiste Coudurier
<baptiste.coudurier at gmail.com> wrote:
>
> On 11/10/2009 12:10 PM, Thilo Borgmann wrote:
>>
>> Baptiste Coudurier schrieb:
>>>
>>> On 10/11/2009 03:04 AM, Thilo Borgmann wrote:
>>>>
>>>> Baptiste Coudurier schrieb:
>>>>>
>>>>> On 10/9/09 1:48 PM, Alex Converse wrote:
>>>>>>
>>>>>> On Sun, Aug 23, 2009 at 3:51 PM, Thilo Borgmann
>>>>>> <thilo.borgmann at googlemail.com> ? ?wrote:
>>>>>>>
[...]
>>>> Index: libavformat/mov.c
>>>> ===================================================================
>>>> --- libavformat/mov.c ? ?(revision 20011)
>>>> +++ libavformat/mov.c ? ?(working copy)
>>>> @@ -434,9 +434,13 @@
>>>> ? ? ? ? ? ? ? ? ? MPEG4AudioConfig cfg;
>>>> ? ? ? ? ? ? ? ? ? ff_mpeg4audio_get_config(&cfg, st->codec->extradata,
>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?st->codec->extradata_size);
>>>> + ? ? ? ? ? ? ? ?if (cfg.chan_config) {
>>>> ? ? ? ? ? ? ? ? ? if (cfg.chan_config> ? 7)
>>>> ? ? ? ? ? ? ? ? ? ? ? return -1;
>>>> ? ? ? ? ? ? ? ? ? st->codec->channels =
>>>> ff_mpeg4audio_channels[cfg.chan_config];
>>>> + ? ? ? ? ? ? ? ?} else {
>>>> + ? ? ? ? ? ? ? ? ? ?st->codec->channels = cfg.channels;
>>>> + ? ? ? ? ? ? ? ?}
>>>
>>> By always setting cfg.channels I wanted to avoid the
>>> if (cfg.chan_config) ...
>>>
>>> That's ok though.
>>>
>>
>> Hm I tried to but cannot really follow the arguing about setting
>> cfg.channels. Do you mean to always set
>>
>> st->codec->channels = cfg.channels;
>>
>> ? This would set it to 0 (for PCE streams == !ALS) but don't we loose
>> something from ff_mpeg4audio_channes[] in that case? And are PCE streams
>> always given if ALS is not given?
>
> What do we loose ? It seems that chan_config value is still set, and it avoids duplicating this if everywhere.

Has it been confirmed that this doesn't break any of the ways that AAC
or MP4A can be muxed into mov-realted formats that we support?
Particularly:
MP4 objectTypeIndication 0x66/0x67
MP4 objectTypeIndication 0x40 AOT_LC channel_config = 0
MP4 objectTypeIndication 0x40 AOT_LC channel_config > 0
MP4?objectTypeIndication 0x40 AOT_L1/L2/L3
MP4?objectTypeIndication 0x40 AOT_PS (Old mp3on4)
AAC in mov?