/*****************************************************************************
- * audio_output.h : audio output interface
+ * vlc_aout.h : audio output interface
*****************************************************************************
- * Copyright (C) 2002-2005 the VideoLAN team
- * $Id$
+ * Copyright (C) 2002-2011 VLC authors and VideoLAN
*
* Authors: Christophe Massiot <massiot@via.ecp.fr>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
*
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
*****************************************************************************/
#ifndef VLC_AOUT_H
* This file defines functions, structures and macros for audio output object
*/
-# ifdef __cplusplus
-extern "C" {
-# endif
+/* Buffers which arrive in advance of more than AOUT_MAX_ADVANCE_TIME
+ * will be considered as bogus and be trashed */
+#define AOUT_MAX_ADVANCE_TIME (AOUT_MAX_PREPARE_TIME + CLOCK_FREQ)
+
+/* Buffers which arrive in advance of more than AOUT_MAX_PREPARE_TIME
+ * will cause the calling thread to sleep */
+#define AOUT_MAX_PREPARE_TIME (2 * CLOCK_FREQ)
+
+/* Buffers which arrive after pts - AOUT_MIN_PREPARE_TIME will be trashed
+ * to avoid too heavy resampling */
+#define AOUT_MIN_PREPARE_TIME AOUT_MAX_PTS_ADVANCE
+
+/* Tolerance values from EBU Recommendation 37 */
+/** Maximum advance of actual audio playback time to coded PTS,
+ * above which downsampling will be performed */
+#define AOUT_MAX_PTS_ADVANCE (CLOCK_FREQ / 25)
+
+/** Maximum delay of actual audio playback time from coded PTS,
+ * above which upsampling will be performed */
+#define AOUT_MAX_PTS_DELAY (3 * CLOCK_FREQ / 50)
+
+/* Max acceptable resampling (in %) */
+#define AOUT_MAX_RESAMPLING 10
#include "vlc_es.h"
#define AOUT_FMTS_IDENTICAL( p_first, p_second ) ( \
((p_first)->i_format == (p_second)->i_format) \
- && ((p_first)->i_rate == (p_second)->i_rate) \
- && ((p_first)->i_physical_channels == (p_second)->i_physical_channels)\
- && ((p_first)->i_original_channels == (p_second)->i_original_channels) )
+ && AOUT_FMTS_SIMILAR(p_first, p_second) )
/* Check if i_rate == i_rate and i_channels == i_channels */
#define AOUT_FMTS_SIMILAR( p_first, p_second ) ( \
&& ((p_first)->i_physical_channels == (p_second)->i_physical_channels)\
&& ((p_first)->i_original_channels == (p_second)->i_original_channels) )
+#define AOUT_FMT_LINEAR( p_format ) \
+ (aout_BitsPerSample((p_format)->i_format) != 0)
+
#define VLC_CODEC_SPDIFL VLC_FOURCC('s','p','d','i')
#define VLC_CODEC_SPDIFB VLC_FOURCC('s','p','d','b')
-#define AOUT_FMT_NON_LINEAR( p_format ) \
+#define AOUT_FMT_SPDIF( p_format ) \
( ((p_format)->i_format == VLC_CODEC_SPDIFL) \
|| ((p_format)->i_format == VLC_CODEC_SPDIFB) \
|| ((p_format)->i_format == VLC_CODEC_A52) \
|| ((p_format)->i_format == VLC_CODEC_DTS) )
-/* This is heavily borrowed from libmad, by Robert Leslie <rob@mars.org> */
-/*
- * Fixed-point format: 0xABBBBBBB
- * A == whole part (sign + 3 bits)
- * B == fractional part (28 bits)
- *
- * Values are signed two's complement, so the effective range is:
- * 0x80000000 to 0x7fffffff
- * -8.0 to +7.9999999962747097015380859375
- *
- * The smallest representable value is:
- * 0x00000001 == 0.0000000037252902984619140625 (i.e. about 3.725e-9)
- *
- * 28 bits of fractional accuracy represent about
- * 8.6 digits of decimal accuracy.
- *
- * Fixed-point numbers can be added or subtracted as normal
- * integers, but multiplication requires shifting the 64-bit result
- * from 56 fractional bits back to 28 (and rounding.)
- */
-typedef int32_t vlc_fixed_t;
-#define FIXED32_FRACBITS 28
-#define FIXED32_MIN ((vlc_fixed_t) -0x80000000L)
-#define FIXED32_MAX ((vlc_fixed_t) +0x7fffffffL)
-#define FIXED32_ONE ((vlc_fixed_t) 0x10000000)
-
-/*
- * Channels descriptions
- */
-
-/* Values available for physical and original channels */
-#define AOUT_CHAN_CENTER 0x1
-#define AOUT_CHAN_LEFT 0x2
-#define AOUT_CHAN_RIGHT 0x4
-#define AOUT_CHAN_REARCENTER 0x10
-#define AOUT_CHAN_REARLEFT 0x20
-#define AOUT_CHAN_REARRIGHT 0x40
-#define AOUT_CHAN_MIDDLELEFT 0x100
-#define AOUT_CHAN_MIDDLERIGHT 0x200
-#define AOUT_CHAN_LFE 0x1000
-
-/* Values available for original channels only */
-#define AOUT_CHAN_DOLBYSTEREO 0x10000
-#define AOUT_CHAN_DUALMONO 0x20000
-#define AOUT_CHAN_REVERSESTEREO 0x40000
-
-#define AOUT_CHAN_PHYSMASK 0xFFFF
-#define AOUT_CHAN_MAX 9
-
-/* Values used for the audio-device and audio-channels object variables */
-#define AOUT_VAR_MONO 1
-#define AOUT_VAR_STEREO 2
-#define AOUT_VAR_2F2R 4
-#define AOUT_VAR_3F2R 5
-#define AOUT_VAR_5_1 6
-#define AOUT_VAR_6_1 7
-#define AOUT_VAR_7_1 8
-#define AOUT_VAR_SPDIF 10
-
+/* Values used for the audio-channels object variable */
+#define AOUT_VAR_CHAN_UNSET 0 /* must be zero */
#define AOUT_VAR_CHAN_STEREO 1
#define AOUT_VAR_CHAN_RSTEREO 2
#define AOUT_VAR_CHAN_LEFT 3
* Main audio output structures
*****************************************************************************/
-#define aout_BufferFree( buffer ) block_Release( buffer )
-
/* Size of a frame for S/PDIF output. */
#define AOUT_SPDIF_SIZE 6144
/* Number of samples in an A/52 frame. */
#define A52_FRAME_NB 1536
-/* Max input rate factor (1/4 -> 4) */
-#define AOUT_MAX_INPUT_RATE (4)
-
-/** allocation of memory in the audio output */
-typedef struct aout_alloc_t
-{
- bool b_alloc;
- int i_bytes_per_sec;
-} aout_alloc_t;
-
-/** audio output buffer FIFO */
-struct aout_fifo_t
-{
- aout_buffer_t * p_first;
- aout_buffer_t ** pp_last;
- date_t end_date;
-};
-
/* FIXME to remove once aout.h is cleaned a bit more */
-#include <vlc_aout_mixer.h>
#include <vlc_block.h>
-/** audio output filter */
-typedef struct aout_filter_owner_sys_t aout_filter_owner_sys_t;
-typedef struct aout_filter_sys_t aout_filter_sys_t;
-struct aout_filter_t
+/** Audio output object */
+struct audio_output
{
VLC_COMMON_MEMBERS
- module_t * p_module;
- aout_filter_sys_t *p_sys;
-
- es_format_t fmt_in;
- es_format_t fmt_out;
-
- aout_alloc_t output_alloc;
-
- bool b_in_place;
- bool b_continuity;
-
- void (*pf_do_work)( aout_instance_t *, aout_filter_t *,
- aout_buffer_t *, aout_buffer_t * );
-
- /* Private structure for the owner of the filter */
- aout_filter_owner_sys_t *p_owner;
-};
-
-#define AOUT_RESAMPLING_NONE 0
-#define AOUT_RESAMPLING_UP 1
-#define AOUT_RESAMPLING_DOWN 2
-
-/** an output stream for the audio output */
-typedef struct aout_output_t
-{
- audio_sample_format_t output;
- /* Indicates whether the audio output is currently starving, to avoid
- * printing a 1,000 "output is starving" messages. */
- bool b_starving;
-
- /* post-filters */
- aout_filter_t * pp_filters[AOUT_MAX_FILTERS];
- int i_nb_filters;
-
- aout_fifo_t fifo;
-
- struct module_t * p_module;
- struct aout_sys_t * p_sys;
- void (* pf_play)( aout_instance_t * );
- int (* pf_volume_get )( aout_instance_t *, audio_volume_t * );
- int (* pf_volume_set )( aout_instance_t *, audio_volume_t );
- int i_nb_samples;
-
- /* Current volume for the output - it's just a placeholder, the plug-in
- * may or may not use it. */
- audio_volume_t i_volume;
-
- /* If b_error == 1, there is no audio output pipeline. */
- bool b_error;
-} aout_output_t;
-
-/** audio output thread descriptor */
-struct aout_instance_t
-{
- VLC_COMMON_MEMBERS
-
- /* Locks : please note that if you need several of these locks, it is
- * mandatory (to avoid deadlocks) to take them in the following order :
- * mixer_lock, p_input->lock, output_fifo_lock, input_fifos_lock.
- * --Meuuh */
- /* When input_fifos_lock is taken, none of the p_input->fifo structures
- * can be read or modified by a third-party thread. */
- vlc_mutex_t input_fifos_lock;
- /* When mixer_lock is taken, all decoder threads willing to mix a
- * buffer must wait until it is released. The output pipeline cannot
- * be modified. No input stream can be added or removed. */
- vlc_mutex_t mixer_lock;
- /* When output_fifo_lock is taken, the p_aout->output.fifo structure
- * cannot be read or written by a third-party thread. */
- vlc_mutex_t output_fifo_lock;
-
- /* Input streams & pre-filters */
- aout_input_t * pp_inputs[AOUT_MAX_INPUTS];
- int i_nb_inputs;
-
- /* Mixer */
- audio_sample_format_t mixer_format;
- aout_alloc_t mixer_allocation;
- float mixer_multiplier;
- aout_mixer_t *p_mixer;
-
- /* Output plug-in */
- aout_output_t output;
+ struct aout_sys_t *sys; /**< Private data for callbacks */
+
+ int (*start)(audio_output_t *, audio_sample_format_t *fmt);
+ /**< Starts a new stream (mandatory, cannot be NULL).
+ * \param fmt input stream sample format upon entry,
+ * output stream sample format upon return [IN/OUT]
+ * \return VLC_SUCCESS on success, non-zero on failure
+ * \note No other stream may be already started when called.
+ */
+ void (*stop)(audio_output_t *);
+ /**< Stops the existing stream (optional, may be NULL).
+ * \note A stream must have been started when called.
+ */
+ int (*time_get)(audio_output_t *, mtime_t *delay);
+ /**< Estimates playback buffer latency (optional, may be NULL).
+ * \param delay pointer to the delay until the next sample to be written
+ * to the playback buffer is rendered [OUT]
+ * \return 0 on success, non-zero on failure or lack of data
+ * \note A stream must have been started when called.
+ */
+ void (*play)(audio_output_t *, block_t *);
+ /**< Queues a block of samples for playback (mandatory, cannot be NULL).
+ * \note A stream must have been started when called.
+ */
+ void (*pause)( audio_output_t *, bool pause, mtime_t date);
+ /**< Pauses or resumes playback (optional, may be NULL).
+ * \param pause pause if true, resume from pause if false
+ * \param date timestamp when the pause or resume was requested
+ * \note A stream must have been started when called.
+ */
+ void (*flush)( audio_output_t *, bool wait);
+ /**< Flushes or drains the playback buffers (mandatory, cannot be NULL).
+ * \param wait true to wait for playback of pending buffers (drain),
+ * false to discard pending buffers (flush)
+ * \note A stream must have been started when called.
+ */
+ int (*volume_set)(audio_output_t *, float volume);
+ /**< Changes playback volume (optional, may be NULL).
+ * \param volume requested volume (0. = mute, 1. = nominal)
+ * \note The volume is always a positive number.
+ * \warning A stream may or may not have been started when called.
+ */
+ int (*mute_set)(audio_output_t *, bool mute);
+ /**< Changes muting (optinal, may be NULL).
+ * \param mute true to mute, false to unmute
+ * \warning A stream may or may not have been started when called.
+ */
+ int (*device_select)(audio_output_t *, const char *id);
+ /**< Selects an audio output device (optional, may be NULL).
+ * \param id nul-terminated device unique identifier.
+ * \return 0 on success, non-zero on failure.
+ * \warning A stream may or may not have been started when called.
+ */
+ struct {
+ void (*volume_report)(audio_output_t *, float);
+ void (*mute_report)(audio_output_t *, bool);
+ void (*policy_report)(audio_output_t *, bool);
+ void (*device_report)(audio_output_t *, const char *);
+ void (*hotplug_report)(audio_output_t *, const char *, const char *);
+ int (*gain_request)(audio_output_t *, float);
+ void (*restart_request)(audio_output_t *, unsigned);
+ } event;
};
/**
- * It describes the audio channel order VLC except.
+ * It describes the audio channel order VLC expect.
*/
static const uint32_t pi_vlc_chan_order_wg4[] =
{
AOUT_CHAN_CENTER, AOUT_CHAN_LFE, 0
};
+#define AOUT_RESTART_FILTERS 1
+#define AOUT_RESTART_OUTPUT 2
+#define AOUT_RESTART_DECODER 4
+
/*****************************************************************************
* Prototypes
*****************************************************************************/
-VLC_EXPORT( aout_buffer_t *, aout_OutputNextBuffer, ( aout_instance_t *, mtime_t, bool ) LIBVLC_USED );
-
/**
* This function computes the reordering needed to go from pi_chan_order_in to
* pi_chan_order_out.
* If pi_chan_order_in or pi_chan_order_out is NULL, it will assume that vlc
* internal (WG4) order is requested.
*/
-VLC_EXPORT( int, aout_CheckChannelReorder, ( const uint32_t *pi_chan_order_in, const uint32_t *pi_chan_order_out, uint32_t i_channel_mask, int i_channels, int *pi_chan_table ) );
-VLC_EXPORT( void, aout_ChannelReorder, ( uint8_t *, int, int, const int *, int ) );
+VLC_API unsigned aout_CheckChannelReorder( const uint32_t *, const uint32_t *,
+ uint32_t mask, uint8_t *table );
+VLC_API void aout_ChannelReorder(void *, size_t, uint8_t, const uint8_t *, vlc_fourcc_t);
+
+VLC_API void aout_Interleave(void *dst, const void *const *planes,
+ unsigned samples, unsigned channels,
+ vlc_fourcc_t fourcc);
+VLC_API void aout_Deinterleave(void *dst, const void *src, unsigned samples,
+ unsigned channels, vlc_fourcc_t fourcc);
/**
- * This fonction will compute the extraction parameter into pi_selection to go
+ * This function will compute the extraction parameter into pi_selection to go
* from i_channels with their type given by pi_order_src[] into the order
* describe by pi_order_dst.
* It will also set :
* by VLC. In this case the channel type pi_order_src[] must be set to 0.
* XXX It must also be used if multiple channels have the same type.
*/
-VLC_EXPORT( bool, aout_CheckChannelExtraction, ( int *pi_selection, uint32_t *pi_layout, int *pi_channels, const uint32_t pi_order_dst[AOUT_CHAN_MAX], const uint32_t *pi_order_src, int i_channels ) );
+VLC_API bool aout_CheckChannelExtraction( int *pi_selection, uint32_t *pi_layout, int *pi_channels, const uint32_t pi_order_dst[AOUT_CHAN_MAX], const uint32_t *pi_order_src, int i_channels );
/**
* Do the actual channels extraction using the parameters created by
* XXX this function does not work in place (p_dst and p_src must not overlap).
* XXX Only 8, 16, 24, 32, 64 bits per sample are supported.
*/
-VLC_EXPORT( void, aout_ChannelExtract, ( void *p_dst, int i_dst_channels, const void *p_src, int i_src_channels, int i_sample_count, const int *pi_selection, int i_bits_per_sample ) );
+VLC_API void aout_ChannelExtract( void *p_dst, int i_dst_channels, const void *p_src, int i_src_channels, int i_sample_count, const int *pi_selection, int i_bits_per_sample );
/* */
-VLC_EXPORT( unsigned int, aout_FormatNbChannels, ( const audio_sample_format_t * p_format ) LIBVLC_USED );
-VLC_EXPORT( unsigned int, aout_BitsPerSample, ( vlc_fourcc_t i_format ) LIBVLC_USED );
-VLC_EXPORT( void, aout_FormatPrepare, ( audio_sample_format_t * p_format ) );
-VLC_EXPORT( void, aout_FormatPrint, ( aout_instance_t * p_aout, const char * psz_text, const audio_sample_format_t * p_format ) );
-VLC_EXPORT( const char *, aout_FormatPrintChannels, ( const audio_sample_format_t * ) LIBVLC_USED );
-
-VLC_EXPORT( mtime_t, aout_FifoFirstDate, ( aout_instance_t *, aout_fifo_t * ) LIBVLC_USED );
-VLC_EXPORT( aout_buffer_t *, aout_FifoPop, ( aout_instance_t * p_aout, aout_fifo_t * p_fifo ) LIBVLC_USED );
-
-/* From intf.c : */
-VLC_EXPORT( void, aout_VolumeSoftInit, ( aout_instance_t * ) );
-VLC_EXPORT( void, aout_VolumeNoneInit, ( aout_instance_t * ) );
-#define aout_VolumeGet(a, b) __aout_VolumeGet(VLC_OBJECT(a), b)
-VLC_EXPORT( int, __aout_VolumeGet, ( vlc_object_t *, audio_volume_t * ) );
-#define aout_VolumeSet(a, b) __aout_VolumeSet(VLC_OBJECT(a), b)
-VLC_EXPORT( int, __aout_VolumeSet, ( vlc_object_t *, audio_volume_t ) );
-#define aout_VolumeUp(a, b, c) __aout_VolumeUp(VLC_OBJECT(a), b, c)
-VLC_EXPORT( int, __aout_VolumeUp, ( vlc_object_t *, int, audio_volume_t * ) );
-#define aout_VolumeDown(a, b, c) __aout_VolumeDown(VLC_OBJECT(a), b, c)
-VLC_EXPORT( int, __aout_VolumeDown, ( vlc_object_t *, int, audio_volume_t * ) );
-#define aout_ToggleMute(a, b) __aout_ToggleMute(VLC_OBJECT(a), b)
-VLC_EXPORT( int, __aout_ToggleMute, ( vlc_object_t *, audio_volume_t * ) );
-VLC_EXPORT( int, aout_FindAndRestart, ( vlc_object_t *, const char *, vlc_value_t, vlc_value_t, void * ) );
-VLC_EXPORT( int, aout_ChannelsRestart, ( vlc_object_t *, const char *, vlc_value_t, vlc_value_t, void * ) );
-
-VLC_EXPORT( void, aout_EnableFilter, (vlc_object_t *, const char *, bool ));
-#define aout_EnableFilter( o, n, b ) \
- aout_EnableFilter( VLC_OBJECT(o), n, b )
+static inline unsigned aout_FormatNbChannels(const audio_sample_format_t *fmt)
+{
+ return popcount(fmt->i_physical_channels);
+}
-/* */
-VLC_EXPORT( vout_thread_t *, aout_filter_RequestVout, ( aout_filter_t *, vout_thread_t *p_vout, video_format_t *p_fmt ) );
+VLC_API unsigned int aout_BitsPerSample( vlc_fourcc_t i_format ) VLC_USED;
+VLC_API void aout_FormatPrepare( audio_sample_format_t * p_format );
+VLC_API void aout_FormatPrint(vlc_object_t *, const char *,
+ const audio_sample_format_t *);
+#define aout_FormatPrint(o, t, f) aout_FormatPrint(VLC_OBJECT(o), t, f)
+VLC_API const char * aout_FormatPrintChannels( const audio_sample_format_t * ) VLC_USED;
+
+VLC_API float aout_VolumeGet (audio_output_t *);
+VLC_API int aout_VolumeSet (audio_output_t *, float);
+VLC_API int aout_MuteGet (audio_output_t *);
+VLC_API int aout_MuteSet (audio_output_t *, bool);
+VLC_API char *aout_DeviceGet (audio_output_t *);
+VLC_API int aout_DeviceSet (audio_output_t *, const char *);
+VLC_API int aout_DevicesList (audio_output_t *, char ***, char ***);
+
+/**
+ * Report change of configured audio volume to the core and UI.
+ */
+static inline void aout_VolumeReport(audio_output_t *aout, float volume)
+{
+ aout->event.volume_report(aout, volume);
+}
+
+/**
+ * Report change of muted flag to the core and UI.
+ */
+static inline void aout_MuteReport(audio_output_t *aout, bool mute)
+{
+ aout->event.mute_report(aout, mute);
+}
+
+/**
+ * Report audio policy status.
+ * \parm cork true to request a cork, false to undo any pending cork.
+ */
+static inline void aout_PolicyReport(audio_output_t *aout, bool cork)
+{
+ aout->event.policy_report(aout, cork);
+}
+
+/**
+ * Report change of output device.
+ */
+static inline void aout_DeviceReport(audio_output_t *aout, const char *id)
+{
+ aout->event.device_report(aout, id);
+}
+
+/**
+ * Report a device hot-plug event.
+ * @param id device ID
+ * @param name human-readable device name (NULL for hot unplug)
+ */
+static inline void aout_HotplugReport(audio_output_t *aout,
+ const char *id, const char *name)
+{
+ aout->event.hotplug_report(aout, id, name);
+}
+
+/**
+ * Request a change of software audio amplification.
+ * \param gain linear amplitude gain (must be positive)
+ * \warning Values in excess 1.0 may cause overflow and distorsion.
+ */
+static inline int aout_GainRequest(audio_output_t *aout, float gain)
+{
+ return aout->event.gain_request(aout, gain);
+}
+
+static inline void aout_RestartRequest(audio_output_t *aout, unsigned mode)
+{
+ aout->event.restart_request(aout, mode);
+}
+
+static inline int aout_ChannelsRestart (vlc_object_t *obj, const char *varname,
+ vlc_value_t oldval, vlc_value_t newval, void *data)
+{
+ audio_output_t *aout = (audio_output_t *)obj;
+ (void)varname; (void)oldval; (void)newval; (void)data;
-# ifdef __cplusplus
+ aout_RestartRequest (aout, AOUT_RESTART_OUTPUT);
+ return 0;
}
-# endif
-#endif /* _VLC_AOUT_H */
+/* Audio output filters */
+typedef struct aout_filters aout_filters_t;
+typedef struct aout_request_vout aout_request_vout_t;
+
+VLC_API aout_filters_t *aout_FiltersNew(vlc_object_t *,
+ const audio_sample_format_t *,
+ const audio_sample_format_t *,
+ const aout_request_vout_t *) VLC_USED;
+#define aout_FiltersNew(o,inf,outf,rv) \
+ aout_FiltersNew(VLC_OBJECT(o),inf,outf,rv)
+VLC_API void aout_FiltersDelete(vlc_object_t *, aout_filters_t *);
+#define aout_FiltersDelete(o,f) \
+ aout_FiltersDelete(VLC_OBJECT(o),f)
+VLC_API bool aout_FiltersAdjustResampling(aout_filters_t *, int);
+VLC_API block_t *aout_FiltersPlay(aout_filters_t *, block_t *, int rate);
+
+VLC_API vout_thread_t * aout_filter_RequestVout( filter_t *, vout_thread_t *p_vout, video_format_t *p_fmt );
+
+#endif /* VLC_AOUT_H */
projects / vlc / blobdiff