#include <iostream>
#include <stdint.h>
#include <boost/lexical_cast.hpp>
+#include <sndfile.h>
extern "C" {
-#include <tiffio.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
-#include <libswscale/swscale.h>
-#include <libpostproc/postprocess.h>
}
-#include <sndfile.h>
#include "film.h"
-#include "format.h"
-#include "transcoder.h"
-#include "job.h"
#include "filter.h"
#include "exceptions.h"
#include "image.h"
#include "ffmpeg_decoder.h"
#include "filter_graph.h"
#include "subtitle.h"
+#include "audio_buffers.h"
#include "i18n.h"
using std::vector;
using std::stringstream;
using std::list;
+using std::min;
using boost::shared_ptr;
using boost::optional;
using boost::dynamic_pointer_cast;
using libdcp::Size;
-FFmpegDecoder::FFmpegDecoder (shared_ptr<const Film> f, shared_ptr<const FFmpegContent> c, bool video, bool audio, bool subtitles, bool video_sync)
+FFmpegDecoder::FFmpegDecoder (shared_ptr<const Film> f, shared_ptr<const FFmpegContent> c, bool video, bool audio)
: Decoder (f)
, VideoDecoder (f)
, AudioDecoder (f)
- , _ffmpeg_content (c)
- , _format_context (0)
- , _video_stream (-1)
- , _frame (0)
- , _video_codec_context (0)
- , _video_codec (0)
- , _audio_codec_context (0)
- , _audio_codec (0)
+ , FFmpeg (c)
, _subtitle_codec_context (0)
, _subtitle_codec (0)
, _decode_video (video)
, _decode_audio (audio)
- , _decode_subtitles (subtitles)
- , _video_sync (video_sync)
+ , _pts_offset (0)
{
- setup_general ();
- setup_video ();
- setup_audio ();
setup_subtitle ();
- if (!video_sync) {
- _first_video = 0;
+ if (video && audio && c->audio_stream() && c->first_video() && c->audio_stream()->first_audio) {
+ _pts_offset = compute_pts_offset (c->first_video().get(), c->audio_stream()->first_audio.get(), c->video_frame_rate());
}
}
-FFmpegDecoder::~FFmpegDecoder ()
+double
+FFmpegDecoder::compute_pts_offset (double first_video, double first_audio, float video_frame_rate)
{
- if (_audio_codec_context) {
- avcodec_close (_audio_codec_context);
- }
+ double const old_first_video = first_video;
- if (_video_codec_context) {
- avcodec_close (_video_codec_context);
- }
-
- if (_subtitle_codec_context) {
- avcodec_close (_subtitle_codec_context);
- }
-
- av_free (_frame);
-
- avformat_close_input (&_format_context);
-}
-
-void
-FFmpegDecoder::setup_general ()
-{
- av_register_all ();
-
- if (avformat_open_input (&_format_context, _ffmpeg_content->file().string().c_str(), 0, 0) < 0) {
- throw OpenFileError (_ffmpeg_content->file().string ());
+ /* Round the first video to a frame boundary */
+ if (fabs (rint (first_video * video_frame_rate) - first_video * video_frame_rate) > 1e-6) {
+ first_video = ceil (first_video * video_frame_rate) / video_frame_rate;
}
- if (avformat_find_stream_info (_format_context, 0) < 0) {
- throw DecodeError (_("could not find stream information"));
- }
-
- /* Find video, audio and subtitle streams */
-
- for (uint32_t i = 0; i < _format_context->nb_streams; ++i) {
- AVStream* s = _format_context->streams[i];
- if (s->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
- _video_stream = i;
- } else if (s->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
-
- /* This is a hack; sometimes it seems that _audio_codec_context->channel_layout isn't set up,
- so bodge it here. No idea why we should have to do this.
- */
-
- if (s->codec->channel_layout == 0) {
- s->codec->channel_layout = av_get_default_channel_layout (s->codec->channels);
- }
-
- _audio_streams.push_back (
- FFmpegAudioStream (stream_name (s), i, s->codec->sample_rate, s->codec->channel_layout)
- );
-
- } else if (s->codec->codec_type == AVMEDIA_TYPE_SUBTITLE) {
- _subtitle_streams.push_back (FFmpegSubtitleStream (stream_name (s), i));
- }
- }
-
- if (_video_stream < 0) {
- throw DecodeError (N_("could not find video stream"));
- }
-
- _frame = avcodec_alloc_frame ();
- if (_frame == 0) {
- throw DecodeError (N_("could not allocate frame"));
- }
+ /* Compute the required offset (also removing any common start delay) */
+ return first_video - old_first_video - min (first_video, first_audio);
}
-void
-FFmpegDecoder::setup_video ()
-{
- _video_codec_context = _format_context->streams[_video_stream]->codec;
- _video_codec = avcodec_find_decoder (_video_codec_context->codec_id);
-
- if (_video_codec == 0) {
- throw DecodeError (_("could not find video decoder"));
- }
-
- if (avcodec_open2 (_video_codec_context, _video_codec, 0) < 0) {
- throw DecodeError (N_("could not open video decoder"));
- }
-}
-
-void
-FFmpegDecoder::setup_audio ()
+FFmpegDecoder::~FFmpegDecoder ()
{
- if (!_ffmpeg_content->audio_stream ()) {
- return;
- }
-
- _audio_codec_context = _format_context->streams[_ffmpeg_content->audio_stream()->id]->codec;
- _audio_codec = avcodec_find_decoder (_audio_codec_context->codec_id);
+ boost::mutex::scoped_lock lm (_mutex);
- if (_audio_codec == 0) {
- throw DecodeError (_("could not find audio decoder"));
- }
-
- if (avcodec_open2 (_audio_codec_context, _audio_codec, 0) < 0) {
- throw DecodeError (N_("could not open audio decoder"));
+ if (_subtitle_codec_context) {
+ avcodec_close (_subtitle_codec_context);
}
-}
+}
void
-FFmpegDecoder::setup_subtitle ()
-{
- if (!_ffmpeg_content->subtitle_stream() || _ffmpeg_content->subtitle_stream()->id >= int (_format_context->nb_streams)) {
- return;
- }
-
- _subtitle_codec_context = _format_context->streams[_ffmpeg_content->subtitle_stream()->id]->codec;
- _subtitle_codec = avcodec_find_decoder (_subtitle_codec_context->codec_id);
-
- if (_subtitle_codec == 0) {
- throw DecodeError (_("could not find subtitle decoder"));
- }
-
- if (avcodec_open2 (_subtitle_codec_context, _subtitle_codec, 0) < 0) {
- throw DecodeError (N_("could not open subtitle decoder"));
- }
-}
-
-
-bool
FFmpegDecoder::pass ()
{
int r = av_read_frame (_format_context, &_packet);
-
+
if (r < 0) {
if (r != AVERROR_EOF) {
/* Maybe we should fail here, but for now we'll just finish off instead */
char buf[256];
av_strerror (r, buf, sizeof(buf));
- _film->log()->log (String::compose (N_("error on av_read_frame (%1) (%2)"), buf, r));
+ shared_ptr<const Film> film = _film.lock ();
+ assert (film);
+ film->log()->log (String::compose (N_("error on av_read_frame (%1) (%2)"), buf, r));
}
-
+
/* Get any remaining frames */
_packet.data = 0;
_packet.size = 0;
-
+
/* XXX: should we reset _packet.data and size after each *_decode_* call? */
-
- int frame_finished;
-
+
if (_decode_video) {
- while (avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet) >= 0 && frame_finished) {
- filter_and_emit_video (_frame);
- }
+ while (decode_video_packet ());
}
if (_ffmpeg_content->audio_stream() && _decode_audio) {
decode_audio_packet ();
}
- return true;
+ /* Stop us being asked for any more data */
+ _video_position = _ffmpeg_content->video_length ();
+ _audio_position = _ffmpeg_content->audio_length ();
+ return;
}
avcodec_get_frame_defaults (_frame);
if (_packet.stream_index == _video_stream && _decode_video) {
-
- int frame_finished;
- int const r = avcodec_decode_video2 (_video_codec_context, _frame, &frame_finished, &_packet);
- if (r >= 0 && frame_finished) {
-
- if (r != _packet.size) {
- _film->log()->log (String::compose (N_("Used only %1 bytes of %2 in packet"), r, _packet.size));
- }
-
- if (_video_sync) {
- out_with_sync ();
- } else {
- filter_and_emit_video (_frame);
- }
- }
-
+ decode_video_packet ();
} else if (_ffmpeg_content->audio_stream() && _packet.stream_index == _ffmpeg_content->audio_stream()->id && _decode_audio) {
decode_audio_packet ();
- } else if (_ffmpeg_content->subtitle_stream() && _packet.stream_index == _ffmpeg_content->subtitle_stream()->id && _decode_subtitles && _first_video) {
+ } else if (_ffmpeg_content->subtitle_stream() && _packet.stream_index == _ffmpeg_content->subtitle_stream()->id) {
+#if 0
int got_subtitle;
AVSubtitle sub;
if (sub.num_rects > 0) {
shared_ptr<TimedSubtitle> ts;
try {
- emit_subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub)));
+ subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub)));
} catch (...) {
/* some problem with the subtitle; we probably didn't understand it */
}
} else {
- emit_subtitle (shared_ptr<TimedSubtitle> ());
+ subtitle (shared_ptr<TimedSubtitle> ());
}
avsubtitle_free (&sub);
}
+#endif
}
-
+
av_free_packet (&_packet);
- return false;
}
/** @param data pointer to array of pointers to buffers.
return audio;
}
-float
-FFmpegDecoder::frames_per_second () const
-{
- AVStream* s = _format_context->streams[_video_stream];
-
- if (s->avg_frame_rate.num && s->avg_frame_rate.den) {
- return av_q2d (s->avg_frame_rate);
- }
-
- return av_q2d (s->r_frame_rate);
-}
-
AVSampleFormat
FFmpegDecoder::audio_sample_format () const
{
- if (_audio_codec_context == 0) {
+ if (!_ffmpeg_content->audio_stream()) {
return (AVSampleFormat) 0;
}
- return _audio_codec_context->sample_fmt;
-}
-
-libdcp::Size
-FFmpegDecoder::native_size () const
-{
- return libdcp::Size (_video_codec_context->width, _video_codec_context->height);
-}
-
-PixelFormat
-FFmpegDecoder::pixel_format () const
-{
- return _video_codec_context->pix_fmt;
+ return audio_codec_context()->sample_fmt;
}
int
-FFmpegDecoder::time_base_numerator () const
+FFmpegDecoder::bytes_per_audio_sample () const
{
- return _video_codec_context->time_base.num;
+ return av_get_bytes_per_sample (audio_sample_format ());
}
-int
-FFmpegDecoder::time_base_denominator () const
+void
+FFmpegDecoder::seek (VideoContent::Frame frame)
{
- return _video_codec_context->time_base.den;
+ do_seek (frame, false, false);
}
-int
-FFmpegDecoder::sample_aspect_ratio_numerator () const
+void
+FFmpegDecoder::seek_back ()
{
- return _video_codec_context->sample_aspect_ratio.num;
+ if (_video_position == 0) {
+ return;
+ }
+
+ do_seek (_video_position - 1, true, true);
}
-int
-FFmpegDecoder::sample_aspect_ratio_denominator () const
+void
+FFmpegDecoder::do_seek (VideoContent::Frame frame, bool backwards, bool accurate)
{
- return _video_codec_context->sample_aspect_ratio.den;
-}
+ int64_t const vt = frame * _ffmpeg_content->video_frame_rate() / av_q2d (_format_context->streams[_video_stream]->time_base);
+ av_seek_frame (_format_context, _video_stream, vt, backwards ? AVSEEK_FLAG_BACKWARD : 0);
+ _video_position = frame;
-string
-FFmpegDecoder::stream_name (AVStream* s) const
-{
- stringstream n;
-
- AVDictionaryEntry const * lang = av_dict_get (s->metadata, N_("language"), 0, 0);
- if (lang) {
- n << lang->value;
- }
-
- AVDictionaryEntry const * title = av_dict_get (s->metadata, N_("title"), 0, 0);
- if (title) {
- if (!n.str().empty()) {
- n << N_(" ");
- }
- n << title->value;
+ avcodec_flush_buffers (video_codec_context());
+ if (_subtitle_codec_context) {
+ avcodec_flush_buffers (_subtitle_codec_context);
}
- if (n.str().empty()) {
- n << N_("unknown");
+ if (accurate) {
+ while (1) {
+ int r = av_read_frame (_format_context, &_packet);
+ if (r < 0) {
+ return;
+ }
+
+ avcodec_get_frame_defaults (_frame);
+
+ if (_packet.stream_index == _video_stream) {
+ int finished = 0;
+ int const r = avcodec_decode_video2 (video_codec_context(), _frame, &finished, &_packet);
+ if (r >= 0 && finished) {
+ int64_t const bet = av_frame_get_best_effort_timestamp (_frame);
+ if (bet > vt) {
+ _video_position = (bet * av_q2d (_format_context->streams[_video_stream]->time_base) + _pts_offset)
+ * _ffmpeg_content->video_frame_rate();
+ break;
+ }
+ }
+ }
+
+ av_free_packet (&_packet);
+ }
}
-
- return n.str ();
}
-int
-FFmpegDecoder::bytes_per_audio_sample () const
+void
+FFmpegDecoder::decode_audio_packet ()
{
- return av_get_bytes_per_sample (audio_sample_format ());
+ /* Audio packets can contain multiple frames, so we may have to call avcodec_decode_audio4
+ several times.
+ */
+
+ AVPacket copy_packet = _packet;
+
+ while (copy_packet.size > 0) {
+
+ int frame_finished;
+ int const decode_result = avcodec_decode_audio4 (audio_codec_context(), _frame, &frame_finished, ©_packet);
+ if (decode_result >= 0) {
+ if (frame_finished) {
+
+ if (_audio_position == 0) {
+ /* Where we are in the source, in seconds */
+ double const pts = av_q2d (_format_context->streams[copy_packet.stream_index]->time_base)
+ * av_frame_get_best_effort_timestamp(_frame) - _pts_offset;
+
+ if (pts > 0) {
+ /* Emit some silence */
+ shared_ptr<AudioBuffers> silence (
+ new AudioBuffers (
+ _ffmpeg_content->audio_channels(),
+ pts * _ffmpeg_content->content_audio_frame_rate()
+ )
+ );
+
+ silence->make_silent ();
+ audio (silence, _audio_position);
+ }
+ }
+
+ copy_packet.data += decode_result;
+ copy_packet.size -= decode_result;
+ }
+ }
+ }
}
-void
-FFmpegDecoder::filter_and_emit_video (AVFrame* frame)
+bool
+FFmpegDecoder::decode_video_packet ()
{
+ int frame_finished;
+ if (avcodec_decode_video2 (video_codec_context(), _frame, &frame_finished, &_packet) < 0 || !frame_finished) {
+ return false;
+ }
+
boost::mutex::scoped_lock lm (_filter_graphs_mutex);
-
- shared_ptr<FilterGraph> graph;
+ shared_ptr<FilterGraph> graph;
+
list<shared_ptr<FilterGraph> >::iterator i = _filter_graphs.begin();
- while (i != _filter_graphs.end() && !(*i)->can_process (libdcp::Size (frame->width, frame->height), (AVPixelFormat) frame->format)) {
+ while (i != _filter_graphs.end() && !(*i)->can_process (libdcp::Size (_frame->width, _frame->height), (AVPixelFormat) _frame->format)) {
++i;
}
if (i == _filter_graphs.end ()) {
- graph.reset (new FilterGraph (_film, this, libdcp::Size (frame->width, frame->height), (AVPixelFormat) frame->format));
+ shared_ptr<const Film> film = _film.lock ();
+ assert (film);
+
+ graph.reset (new FilterGraph (_ffmpeg_content, libdcp::Size (_frame->width, _frame->height), (AVPixelFormat) _frame->format));
_filter_graphs.push_back (graph);
- _film->log()->log (String::compose (N_("New graph for %1x%2, pixel format %3"), frame->width, frame->height, frame->format));
+
+ film->log()->log (String::compose (N_("New graph for %1x%2, pixel format %3"), _frame->width, _frame->height, _frame->format));
} else {
graph = *i;
}
- list<shared_ptr<Image> > images = graph->process (frame);
+ list<shared_ptr<Image> > images = graph->process (_frame);
+ string post_process = Filter::ffmpeg_strings (_ffmpeg_content->filters()).second;
+
for (list<shared_ptr<Image> >::iterator i = images.begin(); i != images.end(); ++i) {
- emit_video (*i, frame_time ());
- }
-}
-
-bool
-FFmpegDecoder::seek (double p)
-{
- return do_seek (p, false);
-}
-
-bool
-FFmpegDecoder::seek_to_last ()
-{
- /* This AVSEEK_FLAG_BACKWARD in do_seek is a bit of a hack; without it, if we ask for a seek to the same place as last time
- (used when we change decoder parameters and want to re-fetch the frame) we end up going forwards rather than
- staying in the same place.
- */
- return do_seek (last_source_time(), true);
-}
-bool
-FFmpegDecoder::do_seek (double p, bool backwards)
-{
- int64_t const vt = p / av_q2d (_format_context->streams[_video_stream]->time_base);
+ shared_ptr<Image> image = *i;
+ if (!post_process.empty ()) {
+ image = image->post_process (post_process, true);
+ }
+
+ int64_t const bet = av_frame_get_best_effort_timestamp (_frame);
+ if (bet != AV_NOPTS_VALUE) {
+
+ double const pts = bet * av_q2d (_format_context->streams[_video_stream]->time_base) - _pts_offset;
+ double const next = _video_position / _ffmpeg_content->video_frame_rate();
+ double const one_frame = 1 / _ffmpeg_content->video_frame_rate ();
+ double delta = pts - next;
+
+ while (delta > one_frame) {
+ /* This PTS is more than one frame forward in time of where we think we should be; emit
+ a black frame.
+ */
+ boost::shared_ptr<Image> black (
+ new SimpleImage (
+ static_cast<AVPixelFormat> (_frame->format),
+ libdcp::Size (video_codec_context()->width, video_codec_context()->height),
+ true
+ )
+ );
+
+ black->make_black ();
+ video (image, false, _video_position);
+ delta -= one_frame;
+ }
- int const r = av_seek_frame (_format_context, _video_stream, vt, backwards ? AVSEEK_FLAG_BACKWARD : 0);
-
- avcodec_flush_buffers (_video_codec_context);
- if (_subtitle_codec_context) {
- avcodec_flush_buffers (_subtitle_codec_context);
+ if (delta > -one_frame) {
+ /* This PTS is within a frame of being right; emit this (otherwise it will be dropped) */
+ video (image, false, _video_position);
+ }
+ } else {
+ shared_ptr<const Film> film = _film.lock ();
+ assert (film);
+ film->log()->log ("Dropping frame without PTS");
+ }
}
-
- return r < 0;
+
+ return true;
}
+
void
-FFmpegDecoder::out_with_sync ()
+FFmpegDecoder::setup_subtitle ()
{
- /* Where we are in the output, in seconds */
- double const out_pts_seconds = video_frame() / frames_per_second();
+ boost::mutex::scoped_lock lm (_mutex);
- /* Where we are in the source, in seconds */
- double const source_pts_seconds = av_q2d (_format_context->streams[_packet.stream_index]->time_base)
- * av_frame_get_best_effort_timestamp(_frame);
-
- _film->log()->log (
- String::compose (N_("Source video frame ready; source at %1, output at %2"), source_pts_seconds, out_pts_seconds),
- Log::VERBOSE
- );
-
- if (!_first_video) {
- _first_video = source_pts_seconds;
- }
-
- /* Difference between where we are and where we should be */
- double const delta = source_pts_seconds - _first_video.get() - out_pts_seconds;
- double const one_frame = 1 / frames_per_second();
-
- /* Insert frames if required to get out_pts_seconds up to pts_seconds */
- if (delta > one_frame) {
- int const extra = rint (delta / one_frame);
- for (int i = 0; i < extra; ++i) {
- repeat_last_video ();
- _film->log()->log (
- String::compose (
- N_("Extra video frame inserted at %1s; source frame %2, source PTS %3 (at %4 fps)"),
- out_pts_seconds, video_frame(), source_pts_seconds, frames_per_second()
- )
- );
- }
- }
-
- if (delta > -one_frame) {
- /* Process this frame */
- filter_and_emit_video (_frame);
- } else {
- /* Otherwise we are omitting a frame to keep things right */
- _film->log()->log (String::compose (N_("Frame removed at %1s"), out_pts_seconds));
+ if (!_ffmpeg_content->subtitle_stream() || _ffmpeg_content->subtitle_stream()->id >= int (_format_context->nb_streams)) {
+ return;
}
-}
-void
-FFmpegDecoder::film_changed (Film::Property p)
-{
- switch (p) {
- case Film::CROP:
- case Film::FILTERS:
- {
- boost::mutex::scoped_lock lm (_filter_graphs_mutex);
- _filter_graphs.clear ();
- }
- break;
+ _subtitle_codec_context = _format_context->streams[_ffmpeg_content->subtitle_stream()->id]->codec;
+ _subtitle_codec = avcodec_find_decoder (_subtitle_codec_context->codec_id);
- default:
- break;
+ if (_subtitle_codec == 0) {
+ throw DecodeError (_("could not find subtitle decoder"));
+ }
+
+ if (avcodec_open2 (_subtitle_codec_context, _subtitle_codec, 0) < 0) {
+ throw DecodeError (N_("could not open subtitle decoder"));
}
}
-/** @return Length (in video frames) according to our content's header */
-ContentVideoFrame
-FFmpegDecoder::video_length () const
-{
- return (double(_format_context->duration) / AV_TIME_BASE) * frames_per_second();
-}
-
-double
-FFmpegDecoder::frame_time () const
+bool
+FFmpegDecoder::done () const
{
- return av_frame_get_best_effort_timestamp(_frame) * av_q2d (_format_context->streams[_video_stream]->time_base);
+ bool const vd = !_decode_video || (_video_position >= _ffmpeg_content->video_length());
+ bool const ad = !_decode_audio || !_ffmpeg_content->audio_stream() || (_audio_position >= _ffmpeg_content->audio_length());
+ return vd && ad;
}
-
-void
-FFmpegDecoder::decode_audio_packet ()
-{
- /* Audio packets can contain multiple frames, so we may have to call avcodec_decode_audio4
- several times.
- */
- AVPacket copy_packet = _packet;
-
- while (copy_packet.size > 0) {
-
- int frame_finished;
- int const decode_result = avcodec_decode_audio4 (_audio_codec_context, _frame, &frame_finished, ©_packet);
- if (decode_result >= 0 && frame_finished) {
-
- /* Where we are in the source, in seconds */
- double const source_pts_seconds = av_q2d (_format_context->streams[copy_packet.stream_index]->time_base)
- * av_frame_get_best_effort_timestamp(_frame);
-
- /* We only decode audio if we've had our first video packet through, and if it
- was before this packet. Until then audio is thrown away.
- */
-
- if ((_first_video && _first_video.get() <= source_pts_seconds) || !_decode_video) {
-
- if (!_first_audio && _decode_video) {
- _first_audio = source_pts_seconds;
-
- /* This is our first audio frame, and if we've arrived here we must have had our
- first video frame. Push some silence to make up any gap between our first
- video frame and our first audio.
- */
-
- /* frames of silence that we must push */
- int const s = rint ((_first_audio.get() - _first_video.get()) * _ffmpeg_content->audio_frame_rate ());
-
- _film->log()->log (
- String::compose (
- N_("First video at %1, first audio at %2, pushing %3 audio frames of silence for %4 channels (%5 bytes per sample)"),
- _first_video.get(), _first_audio.get(), s, _ffmpeg_content->audio_channels(), bytes_per_audio_sample()
- )
- );
-
- if (s) {
- shared_ptr<AudioBuffers> audio (new AudioBuffers (_ffmpeg_content->audio_channels(), s));
- audio->make_silent ();
- Audio (audio);
- }
- }
-
- int const data_size = av_samples_get_buffer_size (
- 0, _audio_codec_context->channels, _frame->nb_samples, audio_sample_format (), 1
- );
-
- assert (_audio_codec_context->channels == _ffmpeg_content->audio_channels());
- Audio (deinterleave_audio (_frame->data, data_size));
- }
- }
-
- if (decode_result >= 0) {
- copy_packet.data += decode_result;
- copy_packet.size -= decode_result;
- }
- }
-}
projects / dcpomatic.git / blobdiff