[vlc-devel] [PATCH] [RFC] add demux filters that are similar in API to regular demuxers
Steve Lhomme
robux4 at gmail.com
Mon Jun 6 11:11:13 CEST 2016
On Sun, Jun 5, 2016 at 2:15 PM, Rémi Denis-Courmont <remi at remlab.net> wrote:
> Le 2016-06-05 13:03, Steve Lhomme a écrit :
>>
>> The only difference is that when control/demux callbacks are called, they
>> are
>> given the next demuxers to call in the chain
>>
>> --
>> replaces https://patches.videolan.org/patch/13585/
>> and https://patches.videolan.org/patch/13615/ with legacy patch remaining
>> I do not understand how some demuxers have pf_demux to NULL, so there
>> might be
>> some simplifications possible.
>> ---
>> NEWS | 3 ++
>> include/vlc_demux.h | 12 ++++++
>> src/input/demux.c | 106
>> ++++++++++++++++++++++++++++++++++++++++++++++++++
>> src/input/demux.h | 3 ++
>> src/input/input.c | 9 +++++
>> src/input/var.c | 1 +
>> src/libvlc-module.c | 5 +++
>> src/playlist/engine.c | 1 +
>> 8 files changed, 140 insertions(+)
>>
>> diff --git a/NEWS b/NEWS
>> index fd5e690..b6eeb06 100644
>> --- a/NEWS
>> +++ b/NEWS
>> @@ -101,6 +101,9 @@ Stream filter:
>> * Added stream prebuffering plugin
>> * Removed HTTP Live streaming stream filter
>> * Added zlib (a.k.a. deflate) decompression filter
>> +
>> +Demux filter:
>> + * Added a demuxer filter chain to filter or intercept control
>> commands and demuxing
>>
>> Audio output:
>> * Complete rewrite of the AudioTrack Android module. This is now
>> the default.
>> diff --git a/include/vlc_demux.h b/include/vlc_demux.h
>> index 1153e1c..0c4bfeb 100644
>> --- a/include/vlc_demux.h
>> +++ b/include/vlc_demux.h
>> @@ -77,16 +77,25 @@ struct demux_t
>>
>> /* Weak link to parent input */
>> input_thread_t *p_input;
>> +
>> + /* demux_t filter chaining */
>> + demux_t *p_next;
>> + demux_t *p_prev;
>
>
> Should not be needed.
For now when a demuxer changes the info values, it calls the previous
demux in line to inform it.
I guess with the demux_InfoXXX() calls they can be chained with a
callback so that we always use the top demuxer and the lower demuxer
doesn't need to know what's before.
>> + int (*pf_filter_demux) ( demux_t *p_this, demux_t *p_next );
>
>
> Just use pf_demux. You can always access p_demux->p_next in the function.
The problem is that in some parts of the code we check if the demuxer
has a pf_demux function.
http://git.videolan.org/?p=vlc.git;a=blob;f=include/vlc_demux.h;h=f4baeea8a5e97c26d956f4ea34d52051620cf788;hb=HEAD#l301
http://git.videolan.org/?p=vlc.git;a=blob;f=src/input/input.c;h=d4acfda036fb6c1c196439f2feea4d3c9a539739;hb=HEAD#l706
http://git.videolan.org/?p=vlc.git;a=blob;f=src/input/input.c;h=d4acfda036fb6c1c196439f2feea4d3c9a539739;hb=HEAD#l2355
I do not understand how a demuxer or an access demuxer can not have
this callback. So for now I copy the pf_demux from the lower demuxer
in the demux filters so it's also seen at the top of the demuxer
chain.
>> };
>>
>> static inline void demux_InfoAddFlags( demux_t *p_demux, int flags )
>> {
>> p_demux->info.i_update |= flags;
>> + if ( p_demux->p_prev )
>> + demux_InfoAddFlags( p_demux->p_prev, flags );
>> }
>
>
> This can cause reentrancy issues.
I'll try to chain the calls and get rid of p_prev.
>>
>> static inline void demux_InfoDelFlags( demux_t *p_demux, int flags )
>> {
>> p_demux->info.i_update &= ~flags;
>> + if ( p_demux->p_prev )
>> + demux_InfoDelFlags( p_demux->p_prev, flags );
>> }
>>
>>
>> @@ -325,6 +334,9 @@ VLC_API int demux_vaControlHelper( stream_t *,
>> int64_t i_start, int64_t i_end,
>>
>> VLC_USED static inline int demux_Demux( demux_t *p_demux )
>> {
>> + if (p_demux->pf_filter_demux)
>> + return p_demux->pf_filter_demux( p_demux, p_demux->p_next );
>> +
>
>
> Should not be needed.
>
>
>> if( !p_demux->pf_demux )
>> return VLC_DEMUXER_SUCCESS;
>>
>> diff --git a/src/input/demux.c b/src/input/demux.c
>> index 303c0b8..6e59c3b 100644
>> --- a/src/input/demux.c
>> +++ b/src/input/demux.c
>> @@ -133,6 +133,9 @@ demux_t *demux_NewAdvanced( vlc_object_t *p_obj,
>> input_thread_t *p_parent_input,
>>
>> p_demux->pf_demux = NULL;
>> p_demux->pf_control = NULL;
>> + p_demux->pf_filter_demux = NULL;
>> + p_demux->p_prev = NULL;
>> + p_demux->p_next = NULL;
>> p_demux->p_sys = NULL;
>> p_demux->info.i_update = 0;
>> p_demux->info.i_title = 0;
>> @@ -342,6 +345,13 @@ void demux_Delete( demux_t *p_demux )
>> {
>> stream_t *s;
>>
>> + demux_t *p_next = p_demux->p_next;
>> + if ( p_next != NULL )
>> + {
>> + p_next->s = NULL; /* demux fiters don't own the stream */
>> + demux_Delete( p_next );
>> + }
>> +
>> module_unneed( p_demux, p_demux->p_module );
>> free( p_demux->psz_file );
>> free( p_demux->psz_location );
>> @@ -656,3 +666,99 @@ static bool SkipAPETag( demux_t *p_demux )
>> return true;
>> }
>>
>> +static demux_t *demux_FilterNew( demux_t *p_wrapped, const char *p_name )
>> +{
>> + demux_t *p_demux = vlc_custom_create( VLC_OBJECT( p_wrapped ),
>> + sizeof( demux_t ),
>> "demux_filter" );
>> + if( unlikely(p_demux == NULL) )
>> + return NULL;
>> +
>> + p_demux->pf_demux = p_wrapped->pf_demux; /* forwarded as
>> it's tested for NULL */
>> + p_demux->pf_control = p_wrapped->pf_control;
>> + p_demux->pf_filter_demux = NULL;
>> + p_demux->p_sys = NULL;
>> + p_demux->s = p_wrapped->s;
>> + p_demux->psz_access = NULL;
>> + p_demux->psz_demux = NULL;
>> + p_demux->psz_location = NULL;
>> + p_demux->psz_file = NULL;
>> + p_demux->p_input = p_wrapped->p_input;
>> + p_demux->out = NULL;
>> + p_demux->p_module =
>> + module_need( p_demux, "demux_filter", p_name, p_name != NULL );
>> +
>> + if( p_demux->p_module == NULL )
>> + goto error;
>> +
>> + assert(p_demux->pf_demux == p_wrapped->pf_demux); /* ensure the
>> NULL test is kept */
>> + p_wrapped->p_prev = p_demux;
>> + p_demux->p_next = p_wrapped;
>> +
>> + return p_demux;
>> +error:
>> + vlc_object_release( p_demux );
>> + return NULL;
>> +}
>> +
>> +demux_t *demux_FilterChainNew( demux_t *p_demux, const char *psz_chain )
>> +{
>> + if( !psz_chain || !*psz_chain )
>> + return NULL; /* add permanent filters */
>> +
>> + char *psz_parser = strdup(psz_chain);
>> + if(!psz_parser)
>> + return NULL;
>> +
>> + vlc_array_t name;
>> + vlc_array_init(&name);
>> +
>> + /* parse chain */
>> + while(psz_parser)
>> + {
>> + config_chain_t *p_cfg;
>> + char *psz_name;
>> + char *psz_rest_chain = config_ChainCreate( &psz_name,
>> &p_cfg, psz_parser );
>> + free( psz_parser );
>> + psz_parser = psz_rest_chain;
>> +
>> + vlc_array_append(&name, psz_name);
>> + config_ChainDestroy(p_cfg);
>> + }
>> +
>> + int i = vlc_array_count(&name);
>> + vlc_array_t module;
>> + vlc_array_init(&module);
>> + while(i--)
>> + {
>> + const char *p_name = vlc_array_item_at_index(&name, i);
>> + demux_t *p_next = demux_FilterNew( p_demux, p_name );
>> + if(!p_next)
>> + goto error;
>> +
>> + vlc_array_append(&module, p_next);
>> + p_demux = p_next;
>> + }
>> +
>> + vlc_array_clear(&name);
>> + vlc_array_clear(&module);
>> +
>> + return p_demux;
>> + error:
>> + i++; /* last module couldn't be created */
>> +
>> + /* destroy all modules created, starting with the last one */
>> + int modules = vlc_array_count(&module);
>> + while(modules--)
>> + demux_Delete(vlc_array_item_at_index(&module, modules));
>> + vlc_array_clear(&module);
>> +
>> + /* then destroy all names and config which weren't destroyed by
>> + * sout_StreamDelete */
>> + while(i--)
>> + {
>> + free(vlc_array_item_at_index(&name, i));
>> + }
>> + vlc_array_clear(&name);
>> +
>> + return NULL;
>> +}
>> diff --git a/src/input/demux.h b/src/input/demux.h
>> index f841f68..24be9b2 100644
>> --- a/src/input/demux.h
>> +++ b/src/input/demux.h
>> @@ -39,4 +39,7 @@ demux_t *demux_NewAdvanced( vlc_object_t *p_obj,
>> input_thread_t *p_parent_input,
>> demux_t *input_DemuxNew( vlc_object_t *, const char *access, const
>> char *demux,
>> const char *path, es_out_t *out, bool quick,
>> input_thread_t * );
>> +
>> +demux_t *demux_FilterChainNew( demux_t *p_demux, const char *psz_name );
>> +
>> #endif
>> diff --git a/src/input/input.c b/src/input/input.c
>> index 5af8256..2169ede 100644
>> --- a/src/input/input.c
>> +++ b/src/input/input.c
>> @@ -2334,6 +2334,15 @@ static input_source_t *InputSourceNew(
>> input_thread_t *p_input,
>> return NULL;
>> }
>>
>> + char *psz_demux_chain = var_GetNonEmptyString(p_input,
>> "demux-filter");
>> + /* add the chain of demux filters */
>> + demux_t *p_filtered_demux = demux_FilterChainNew( in->p_demux,
>> psz_demux_chain );
>> + if ( p_filtered_demux != NULL )
>> + in->p_demux = p_filtered_demux;
>> + else if ( psz_demux_chain != NULL )
>> + msg_Dbg(p_input, "Failed to create demux filter %s",
>> psz_demux_chain);
>> + free( psz_demux_chain );
>> +
>> /* Get infos from (access_)demux */
>> bool b_can_seek;
>> if( demux_Control( in->p_demux, DEMUX_CAN_SEEK, &b_can_seek ) )
>> diff --git a/src/input/var.c b/src/input/var.c
>> index 6534603..437c614 100644
>> --- a/src/input/var.c
>> +++ b/src/input/var.c
>> @@ -513,6 +513,7 @@ void input_ConfigVarInit ( input_thread_t *p_input )
>> /* */
>> var_Create( p_input, "access", VLC_VAR_STRING | VLC_VAR_DOINHERIT );
>> var_Create( p_input, "demux", VLC_VAR_STRING | VLC_VAR_DOINHERIT );
>> + var_Create( p_input, "demux-filter", VLC_VAR_STRING |
>> VLC_VAR_DOINHERIT );
>> var_Create( p_input, "stream-filter", VLC_VAR_STRING |
>> VLC_VAR_DOINHERIT );
>>
>> /* Meta */
>> diff --git a/src/libvlc-module.c b/src/libvlc-module.c
>> index 74fc7e5..5e7be1d 100644
>> --- a/src/libvlc-module.c
>> +++ b/src/libvlc-module.c
>> @@ -980,6 +980,10 @@ static const char *const ppsz_prefres[] = {
>> #define STREAM_FILTER_LONGTEXT N_( \
>> "Stream filters are used to modify the stream that is being read. " )
>>
>> +#define DEMUX_FILTER_TEXT N_("Demux filter module")
>> +#define DEMUX_FILTER_LONGTEXT N_( \
>> + "Demux filters are used to modify/control the stream that is
>> being read. " )
>> +
>> #define DEMUX_TEXT N_("Demux module")
>> #define DEMUX_LONGTEXT N_( \
>> "Demultiplexers are used to separate the \"elementary\" streams " \
>> @@ -1868,6 +1872,7 @@ vlc_module_begin ()
>> add_module_list( "stream-filter", "stream_filter", NULL,
>> STREAM_FILTER_TEXT, STREAM_FILTER_LONGTEXT, false )
>>
>> + add_string( "demux-filter", NULL, DEMUX_FILTER_TEXT,
>> DEMUX_FILTER_LONGTEXT, true )
>>
>> /* Stream output options */
>> set_category( CAT_SOUT )
>> diff --git a/src/playlist/engine.c b/src/playlist/engine.c
>> index 9f3abf0..1ff64c7 100644
>> --- a/src/playlist/engine.c
>> +++ b/src/playlist/engine.c
>> @@ -472,6 +472,7 @@ static void VariablesInit( playlist_t *p_playlist )
>>
>> /* sout variables */
>> var_Create( p_playlist, "sout", VLC_VAR_STRING | VLC_VAR_DOINHERIT );
>> + var_Create( p_playlist, "demux-filter", VLC_VAR_STRING |
>> VLC_VAR_DOINHERIT );
>>
>> /* */
>> var_Create( p_playlist, "album-art", VLC_VAR_INTEGER |
>> VLC_VAR_DOINHERIT );
>
>
> --
> Rémi Denis-Courmont
> http://www.remlab.net/
> _______________________________________________
> vlc-devel mailing list
> To unsubscribe or modify your subscription options:
> https://mailman.videolan.org/listinfo/vlc-devel
More information about the vlc-devel
mailing list