/* $Id: encx264.c,v 1.21 2005/11/04 13:09:41 titer Exp $
-This file is part of the HandBrake source code.
-Homepage: <http://handbrake.m0k.org/>.
-It may be used under the terms of the GNU General Public License. */
+ This file is part of the HandBrake source code.
+ Homepage: <http://handbrake.fr/>.
+ It may be used under the terms of the GNU General Public License. */
#include <stdarg.h>
encx264Close
};
+#define DTS_BUFFER_SIZE 32
+
+/*
+ * The frame info struct remembers information about each frame across calls
+ * to x264_encoder_encode. Since frames are uniquely identified by their
+ * timestamp, we use some bits of the timestamp as an index. The LSB is
+ * chosen so that two successive frames will have different values in the
+ * bits over any plausible range of frame rates. (Starting with bit 8 allows
+ * any frame rate slower than 352fps.) The MSB determines the size of the array.
+ * It is chosen so that two frames can't use the same slot during the
+ * encoder's max frame delay (set by the standard as 16 frames) and so
+ * that, up to some minimum frame rate, frames are guaranteed to map to
+ * different slots. (An MSB of 17 which is 2^(17-8+1) = 1024 slots guarantees
+ * no collisions down to a rate of .7 fps).
+ */
+#define FRAME_INFO_MAX2 (8) // 2^8 = 256; 90000/256 = 352 frames/sec
+#define FRAME_INFO_MIN2 (17) // 2^17 = 128K; 90000/131072 = 1.4 frames/sec
+#define FRAME_INFO_SIZE (1 << (FRAME_INFO_MIN2 - FRAME_INFO_MAX2 + 1))
+#define FRAME_INFO_MASK (FRAME_INFO_SIZE - 1)
+
struct hb_work_private_s
{
hb_job_t * job;
x264_t * x264;
x264_picture_t pic_in;
- x264_picture_t pic_out;
-
+ uint8_t *x264_allocated_pic;
+
+ int chap_mark; // saved chap mark when we're propagating it
+ int64_t last_stop; // Debugging - stop time of previous input frame
+ int64_t init_delay;
+ int64_t next_chap;
+
+ struct {
+ int64_t duration;
+ } frame_info[FRAME_INFO_SIZE];
+
char filename[1024];
};
/***********************************************************************
-* hb_work_encx264_init
-***********************************************************************
-*
-**********************************************************************/
+ * hb_work_encx264_init
+ ***********************************************************************
+ *
+ **********************************************************************/
int encx264Init( hb_work_object_t * w, hb_job_t * job )
{
x264_param_t param;
x264_nal_t * nal;
int nal_count;
- int i, size;
-
+ int nal_size;
+
hb_work_private_t * pv = calloc( 1, sizeof( hb_work_private_t ) );
w->private_data = pv;
-
+
pv->job = job;
-
+
memset( pv->filename, 0, 1024 );
hb_get_tempory_filename( job->h, pv->filename, "x264.log" );
-
+
x264_param_default( ¶m );
-
- param.i_threads = hb_get_cpu_count();
+
+ param.i_threads = ( hb_get_cpu_count() * 3 / 2 );
param.i_width = job->width;
param.i_height = job->height;
param.i_fps_num = job->vrate;
param.i_fps_den = job->vrate_base;
- param.i_keyint_max = 20 * job->vrate / job->vrate_base;
- param.i_log_level = X264_LOG_NONE;
-
+
+ if (job->vrate_base != 1080000)
+ {
+ /* If the fps isn't 25, adjust the key intervals. Add 1 because
+ we want 24, not 23 with a truncated remainder. */
+ param.i_keyint_min = (job->vrate / job->vrate_base) + 1;
+ param.i_keyint_max = (10 * job->vrate / job->vrate_base) + 1;
+ hb_log("encx264: keyint-min: %i, keyint-max: %i", param.i_keyint_min, param.i_keyint_max);
+ }
+
+ param.i_log_level = X264_LOG_INFO;
if( job->h264_level )
{
- param.i_threads = 1;
- param.b_cabac = 0;
- param.i_level_idc = job->h264_level;
- hb_log( "encx264: encoding at level %i",
- param.i_level_idc );
+ param.b_cabac = 0;
+ param.i_level_idc = job->h264_level;
+ hb_log( "encx264: encoding at level %i",
+ param.i_level_idc );
}
-
- /* Slightly faster with minimal quality lost */
- param.analyse.i_subpel_refine = 4;
-
- if( job->vquality >= 0.0 && job->vquality <= 1.0 )
+
+ /*
+ This section passes the string x264opts to libx264 for parsing into
+ parameter names and values.
+
+ The string is set up like this:
+ option1=value1:option2=value 2
+
+ So, you have to iterate through based on the colons, and then put
+ the left side of the equals sign in "name" and the right side into
+ "value." Then you hand those strings off to x264 for interpretation.
+
+ This is all based on the universal x264 option handling Loren
+ Merritt implemented in the Mplayer/Mencoder project.
+ */
+
+ if( job->x264opts != NULL && *job->x264opts != '\0' )
{
- /* Constant QP */
- param.rc.i_qp_constant = 51 - job->vquality * 51;
- hb_log( "encx264: encoding at constant QP %d",
- param.rc.i_qp_constant );
+ char *x264opts, *x264opts_start;
+
+ x264opts = x264opts_start = strdup(job->x264opts);
+
+ while( x264opts_start && *x264opts )
+ {
+ char *name = x264opts;
+ char *value;
+ int ret;
+
+ x264opts += strcspn( x264opts, ":" );
+ if( *x264opts )
+ {
+ *x264opts = 0;
+ x264opts++;
+ }
+
+ value = strchr( name, '=' );
+ if( value )
+ {
+ *value = 0;
+ value++;
+ }
+
+ /*
+ When B-frames are enabled, the max frame count increments
+ by 1 (regardless of the number of B-frames). If you don't
+ change the duration of the video track when you mux, libmp4
+ barfs. So, check if the x264opts are using B-frames, and
+ when they are, set the boolean job->areBframes as true.
+ */
+
+ if( !( strcmp( name, "bframes" ) ) )
+ {
+ if( atoi( value ) > 0 )
+ {
+ job->areBframes = 1;
+ }
+ }
+
+ /* Note b-pyramid here, so the initial delay can be doubled */
+ if( !( strcmp( name, "b-pyramid" ) ) )
+ {
+ if( value != NULL )
+ {
+ if( atoi( value ) > 0 )
+ {
+ job->areBframes = 2;
+ }
+ }
+ else
+ {
+ job->areBframes = 2;
+ }
+ }
+
+ /* Here's where the strings are passed to libx264 for parsing. */
+ ret = x264_param_parse( ¶m, name, value );
+
+ /* Let x264 sanity check the options for us*/
+ if( ret == X264_PARAM_BAD_NAME )
+ hb_log( "x264 options: Unknown suboption %s", name );
+ if( ret == X264_PARAM_BAD_VALUE )
+ hb_log( "x264 options: Bad argument %s=%s", name, value ? value : "(null)" );
+ }
+ free(x264opts_start);
+ }
+
+ /* set up the VUI color model & gamma to match what the COLR atom
+ * set in muxmp4.c says. See libhb/muxmp4.c for notes. */
+ if( job->color_matrix == 1 )
+ {
+ // ITU BT.601 DVD or SD TV content
+ param.vui.i_colorprim = 6;
+ param.vui.i_transfer = 1;
+ param.vui.i_colmatrix = 6;
+ }
+ else if( job->color_matrix == 2 )
+ {
+ // ITU BT.709 HD content
+ param.vui.i_colorprim = 1;
+ param.vui.i_transfer = 1;
+ param.vui.i_colmatrix = 1;
+ }
+ else if ( job->title->width >= 1280 || job->title->height >= 720 )
+ {
+ // we guess that 720p or above is ITU BT.709 HD content
+ param.vui.i_colorprim = 1;
+ param.vui.i_transfer = 1;
+ param.vui.i_colmatrix = 1;
}
else
{
+ // ITU BT.601 DVD or SD TV content
+ param.vui.i_colorprim = 6;
+ param.vui.i_transfer = 1;
+ param.vui.i_colmatrix = 6;
+ }
+
+ if( job->anamorphic.mode )
+ {
+ param.vui.i_sar_width = job->anamorphic.par_width;
+ param.vui.i_sar_height = job->anamorphic.par_height;
+
+ hb_log( "encx264: encoding with stored aspect %d/%d",
+ param.vui.i_sar_width, param.vui.i_sar_height );
+ }
+
- /* Rate control */
- /* no longer in x264 - see rc.i_rc_method in x264.h */
- /* param.rc.b_cbr = 1; */
-
- /* these were the only settings I could use to get accurate ending video bitrate */
- param.rc.i_rc_method = X264_RC_CRF;
- param.rc.i_vbv_max_bitrate = job->vbitrate;
- param.rc.i_vbv_buffer_size = 224;
- param.rc.i_rf_constant = 1;
-
+ if( job->vquality > 0.0 && job->vquality < 1.0 )
+ {
+ switch( job->crf )
+ {
+ case 1:
+ /*Constant RF*/
+ param.rc.i_rc_method = X264_RC_CRF;
+ param.rc.f_rf_constant = 51 - job->vquality * 51;
+ hb_log( "encx264: Encoding at constant RF %f",
+ param.rc.f_rf_constant );
+ break;
+
+ case 0:
+ /*Constant QP*/
+ param.rc.i_rc_method = X264_RC_CQP;
+ param.rc.i_qp_constant = 51 - job->vquality * 51;
+ hb_log( "encx264: encoding at constant QP %d",
+ param.rc.i_qp_constant );
+ break;
+ }
+ }
+ else if( job->vquality == 0 || job->vquality >= 1.0 )
+ {
+ /* Use the vquality as a raw RF or QP
+ instead of treating it like a percentage. */
+ switch( job->crf )
+ {
+ case 1:
+ /*Constant RF*/
+ param.rc.i_rc_method = X264_RC_CRF;
+ param.rc.f_rf_constant = job->vquality;
+ hb_log( "encx264: Encoding at constant RF %f",
+ param.rc.f_rf_constant );
+ break;
+
+ case 0:
+ /*Constant QP*/
+ param.rc.i_rc_method = X264_RC_CQP;
+ param.rc.i_qp_constant = job->vquality;
+ hb_log( "encx264: encoding at constant QP %d",
+ param.rc.i_qp_constant );
+ break;
+ }
+ }
+ else
+ {
+ /* Rate control */
+ param.rc.i_rc_method = X264_RC_ABR;
param.rc.i_bitrate = job->vbitrate;
switch( job->pass )
{
case 1:
- param.rc.i_rc_method = X264_RC_ABR;
param.rc.b_stat_write = 1;
param.rc.psz_stat_out = pv->filename;
break;
case 2:
- param.rc.i_rc_method = X264_RC_ABR;
param.rc.b_stat_read = 1;
param.rc.psz_stat_in = pv->filename;
break;
}
}
-
- hb_log( "encx264: opening libx264 (pass %d)", job->pass );
+
+ hb_deep_log( 2, "encx264: opening libx264 (pass %d)", job->pass );
pv->x264 = x264_encoder_open( ¶m );
-
- w->config->mpeg4.length = 0;
-
+
x264_encoder_headers( pv->x264, &nal, &nal_count );
-
- for( i = 0; i < nal_count; i++ )
- {
- size = sizeof( w->config->mpeg4.bytes ) - w->config->mpeg4.length;
- x264_nal_encode( &w->config->mpeg4.bytes[w->config->mpeg4.length],
- &size, 1, &nal[i] );
- w->config->mpeg4.length += size;
- }
-
+
+ /* Sequence Parameter Set */
+ x264_nal_encode( w->config->h264.sps, &nal_size, 0, &nal[1] );
+ w->config->h264.sps_length = nal_size;
+
+ /* Picture Parameter Set */
+ x264_nal_encode( w->config->h264.pps, &nal_size, 0, &nal[2] );
+ w->config->h264.pps_length = nal_size;
+
x264_picture_alloc( &pv->pic_in, X264_CSP_I420,
job->width, job->height );
-
+
+ pv->pic_in.img.i_stride[2] = pv->pic_in.img.i_stride[1] = ( ( job->width + 1 ) >> 1 );
+ pv->x264_allocated_pic = pv->pic_in.img.plane[0];
+
+ if (job->areBframes)
+ {
+ /* Basic initDelay value is the clockrate divided by the FPS
+ -- the length of one frame in clockticks. */
+ pv->init_delay = 90000. / ((double)job->vrate / (double)job->vrate_base);
+
+ /* 23.976-length frames are 3753.75 ticks long on average but the DVD
+ creates that average rate by repeating 59.95 fields so the max
+ frame size is actually 4504.5 (3 field times). The field durations
+ are computed based on quantized times (see below) so we need an extra
+ two ticks to account for the rounding. */
+ if (pv->init_delay == 3753)
+ pv->init_delay = 4507;
+
+ /* frame rates are not exact in the DVD 90KHz PTS clock (they are
+ exact in the DVD 27MHz system clock but we never see that) so the
+ rates computed above are all +-1 due to quantization. Worst case
+ is when a clock-rounded-down frame is adjacent to a rounded-up frame
+ which makes one of the frames 2 ticks longer than the nominal
+ frame time. */
+ pv->init_delay += 2;
+
+ /* For VFR, libhb sees the FPS as 29.97, but the longest frames
+ will use the duration of frames running at 23.976fps instead.. */
+ if (job->vfr)
+ {
+ pv->init_delay = 7506;
+ }
+
+ /* The delay is 1 frames for regular b-frames, 2 for b-pyramid. */
+ pv->init_delay *= job->areBframes;
+ }
+ w->config->h264.init_delay = pv->init_delay;
+
return 0;
}
void encx264Close( hb_work_object_t * w )
{
hb_work_private_t * pv = w->private_data;
+ /*
+ * Patch the x264 allocated data back in so that x264 can free it
+ * we have been using our own buffers during the encode to avoid copying.
+ */
+ pv->pic_in.img.plane[0] = pv->x264_allocated_pic;
+ x264_picture_clean( &pv->pic_in );
x264_encoder_close( pv->x264 );
-
+ free( pv );
+ w->private_data = NULL;
+
/* TODO */
}
-int encx264Work( hb_work_object_t * w, hb_buffer_t ** buf_in,
- hb_buffer_t ** buf_out )
+/*
+ * see comments in definition of 'frame_info' in pv struct for description
+ * of what these routines are doing.
+ */
+static void save_frame_info( hb_work_private_t * pv, hb_buffer_t * in )
{
- hb_work_private_t * pv = w->private_data;
- hb_job_t * job = pv->job;
- hb_buffer_t * in = *buf_in, * buf;
- int i_nal;
- x264_nal_t * nal;
+ int i = (in->start >> FRAME_INFO_MAX2) & FRAME_INFO_MASK;
+ pv->frame_info[i].duration = in->stop - in->start;
+}
+
+static int64_t get_frame_duration( hb_work_private_t * pv, int64_t pts )
+{
+ int i = (pts >> FRAME_INFO_MAX2) & FRAME_INFO_MASK;
+ return pv->frame_info[i].duration;
+}
+
+static hb_buffer_t *nal_encode( hb_work_object_t *w, x264_picture_t *pic_out,
+ int i_nal, x264_nal_t *nal )
+{
+ hb_buffer_t *buf = NULL;
+ hb_work_private_t *pv = w->private_data;
+ hb_job_t *job = pv->job;
+
+ /* Should be way too large */
+ buf = hb_video_buffer_init( job->width, job->height );
+ buf->size = 0;
+ buf->frametype = 0;
+
+ // use the pts to get the original frame's duration.
+ int64_t duration = get_frame_duration( pv, pic_out->i_pts );
+ buf->start = pic_out->i_pts;
+ buf->stop = pic_out->i_pts + duration;
+
+ /* Encode all the NALs we were given into buf.
+ NOTE: This code assumes one video frame per NAL (but there can
+ be other stuff like SPS and/or PPS). If there are multiple
+ frames we only get the duration of the first which will
+ eventually screw up the muxer & decoder. */
int i;
-
- /* XXX avoid this memcpy ? */
- memcpy( pv->pic_in.img.plane[0], in->data, job->width * job->height );
+ for( i = 0; i < i_nal; i++ )
+ {
+ int data = buf->alloc - buf->size;
+ int size = x264_nal_encode( buf->data + buf->size, &data, 1, &nal[i] );
+ if( size < 1 )
+ {
+ continue;
+ }
+
+ if( job->mux & HB_MUX_AVI )
+ {
+ if( nal[i].i_ref_idc == NAL_PRIORITY_HIGHEST )
+ {
+ buf->frametype = HB_FRAME_KEY;
+ }
+ buf->size += size;
+ continue;
+ }
+
+ /* H.264 in .mp4 or .mkv */
+ int naltype = buf->data[buf->size+4] & 0x1f;
+ if ( naltype == 0x7 || naltype == 0x8 )
+ {
+ // Sequence Parameter Set & Program Parameter Set go in the
+ // mp4 header so skip them here
+ continue;
+ }
+
+ /* H.264 in mp4 (stolen from mp4creator) */
+ buf->data[buf->size+0] = ( ( size - 4 ) >> 24 ) & 0xFF;
+ buf->data[buf->size+1] = ( ( size - 4 ) >> 16 ) & 0xFF;
+ buf->data[buf->size+2] = ( ( size - 4 ) >> 8 ) & 0xFF;
+ buf->data[buf->size+3] = ( ( size - 4 ) >> 0 ) & 0xFF;
+
+ /* Decide what type of frame we have. */
+ switch( pic_out->i_type )
+ {
+ case X264_TYPE_IDR:
+ buf->frametype = HB_FRAME_IDR;
+ /* if we have a chapter marker pending and this
+ frame's presentation time stamp is at or after
+ the marker's time stamp, use this as the
+ chapter start. */
+ if( pv->next_chap != 0 && pv->next_chap <= pic_out->i_pts )
+ {
+ pv->next_chap = 0;
+ buf->new_chap = pv->chap_mark;
+ }
+ break;
+
+ case X264_TYPE_I:
+ buf->frametype = HB_FRAME_I;
+ break;
+
+ case X264_TYPE_P:
+ buf->frametype = HB_FRAME_P;
+ break;
+
+ case X264_TYPE_B:
+ buf->frametype = HB_FRAME_B;
+ break;
+
+ /* This is for b-pyramid, which has reference b-frames
+ However, it doesn't seem to ever be used... */
+ case X264_TYPE_BREF:
+ buf->frametype = HB_FRAME_BREF;
+ break;
+
+ // If it isn't the above, what type of frame is it??
+ default:
+ buf->frametype = 0;
+ break;
+ }
+
+ /* Since libx264 doesn't tell us when b-frames are
+ themselves reference frames, figure it out on our own. */
+ if( (buf->frametype == HB_FRAME_B) &&
+ (nal[i].i_ref_idc != NAL_PRIORITY_DISPOSABLE) )
+ buf->frametype = HB_FRAME_BREF;
+
+ buf->size += size;
+ }
+ // make sure we found at least one video frame
+ if ( buf->size <= 0 )
+ {
+ // no video - discard the buf
+ hb_buffer_close( &buf );
+ }
+ return buf;
+}
+
+static hb_buffer_t *x264_encode( hb_work_object_t *w, hb_buffer_t *in )
+{
+ hb_work_private_t *pv = w->private_data;
+ hb_job_t *job = pv->job;
+
+ /* Point x264 at our current buffers Y(UV) data. */
+ pv->pic_in.img.plane[0] = in->data;
+
+ int uvsize = ( (job->width + 1) >> 1 ) * ( (job->height + 1) >> 1 );
if( job->grayscale )
{
/* XXX x264 has currently no option for grayscale encoding */
- memset( pv->pic_in.img.plane[1], 0x80, job->width * job->height / 4 );
- memset( pv->pic_in.img.plane[2], 0x80, job->width * job->height / 4 );
+ memset( pv->pic_in.img.plane[1], 0x80, uvsize );
+ memset( pv->pic_in.img.plane[2], 0x80, uvsize );
}
else
{
- memcpy( pv->pic_in.img.plane[1], in->data + job->width * job->height,
- job->width * job->height / 4 );
- memcpy( pv->pic_in.img.plane[2], in->data + 5 * job->width *
- job->height / 4, job->width * job->height / 4 );
+ /* Point x264 at our buffers (Y)UV data */
+ pv->pic_in.img.plane[1] = in->data + job->width * job->height;
+ pv->pic_in.img.plane[2] = pv->pic_in.img.plane[1] + uvsize;
}
-
- pv->pic_in.i_type = X264_TYPE_AUTO;
- pv->pic_in.i_qpplus1 = 0;
-
- x264_encoder_encode( pv->x264, &nal, &i_nal,
- &pv->pic_in, &pv->pic_out );
-
-
-
- /* Should be way too large */
- buf = hb_buffer_init( 3 * job->width * job->height / 2 );
- buf->start = in->start;
- buf->stop = in->stop;
- buf->key = ( pv->pic_out.i_type == X264_TYPE_IDR );
-
-
- buf->size = 0;
- for( i = 0; i < i_nal; i++ )
+ if( in->new_chap && job->chapter_markers )
{
- int size, data;
- data = buf->alloc - buf->size;
- if( ( size = x264_nal_encode( &buf->data[buf->size], &data,
- 1, &nal[i] ) ) > 0 )
+ /* chapters have to start with an IDR frame so request that this
+ frame be coded as IDR. Since there may be up to 16 frames
+ currently buffered in the encoder remember the timestamp so
+ when this frame finally pops out of the encoder we'll mark
+ its buffer as the start of a chapter. */
+ pv->pic_in.i_type = X264_TYPE_IDR;
+ if( pv->next_chap == 0 )
{
- buf->size += size;
+ pv->next_chap = in->start;
+ pv->chap_mark = in->new_chap;
}
+ /* don't let 'work_loop' put a chapter mark on the wrong buffer */
+ in->new_chap = 0;
}
-
- *buf_out = buf;
-
- return HB_WORK_OK;
+ else
+ {
+ pv->pic_in.i_type = X264_TYPE_AUTO;
+ }
+ pv->pic_in.i_qpplus1 = 0;
+
+ /* XXX this is temporary debugging code to check that the upstream
+ * modules (render & sync) have generated a continuous, self-consistent
+ * frame stream with the current frame's start time equal to the
+ * previous frame's stop time.
+ */
+ if( pv->last_stop != in->start )
+ {
+ hb_log("encx264 input continuity err: last stop %lld start %lld",
+ pv->last_stop, in->start);
+ }
+ pv->last_stop = in->stop;
+
+ // Remember info about this frame that we need to pass across
+ // the x264_encoder_encode call (since it reorders frames).
+ save_frame_info( pv, in );
+
+ /* Feed the input PTS to x264 so it can figure out proper output PTS */
+ pv->pic_in.i_pts = in->start;
+
+ x264_picture_t pic_out;
+ int i_nal;
+ x264_nal_t *nal;
+
+ x264_encoder_encode( pv->x264, &nal, &i_nal, &pv->pic_in, &pic_out );
+ if ( i_nal > 0 )
+ {
+ return nal_encode( w, &pic_out, i_nal, nal );
+ }
+ return NULL;
}
+int encx264Work( hb_work_object_t * w, hb_buffer_t ** buf_in,
+ hb_buffer_t ** buf_out )
+{
+ hb_work_private_t *pv = w->private_data;
+ hb_buffer_t *in = *buf_in;
+
+ *buf_out = NULL;
+ if( in->size <= 0 )
+ {
+ // EOF on input. Flush any frames still in the decoder then
+ // send the eof downstream to tell the muxer we're done.
+ x264_picture_t pic_out;
+ int i_nal;
+ x264_nal_t *nal;
+ hb_buffer_t *last_buf = NULL;
+
+ while (1)
+ {
+ x264_encoder_encode( pv->x264, &nal, &i_nal, NULL, &pic_out );
+ if ( i_nal <= 0 )
+ break;
+
+ hb_buffer_t *buf = nal_encode( w, &pic_out, i_nal, nal );
+ if ( buf )
+ {
+ if ( last_buf == NULL )
+ *buf_out = buf;
+ else
+ last_buf->next = buf;
+ last_buf = buf;
+ }
+ }
+ // Flushed everything - add the eof to the end of the chain.
+ if ( last_buf == NULL )
+ *buf_out = in;
+ else
+ last_buf->next = in;
+
+ *buf_in = NULL;
+ return HB_WORK_DONE;
+ }
+
+ // Not EOF - encode the packet & wrap it in a NAL
+
+ // if we're re-ordering frames, check if this frame is too large to reorder
+ if ( pv->init_delay && in->stop - in->start > pv->init_delay )
+ {
+ // This frame's duration is larger than the time allotted for b-frame
+ // reordering. That means that if it's used as a reference the decoder
+ // won't be able to move it early enough to render it in correct
+ // sequence & the playback will have odd jumps & twitches. To make
+ // sure this doesn't happen we pretend this frame is multiple
+ // frames, each with duration <= init_delay. Since each of these
+ // new frames contains the same image the visual effect is identical
+ // to the original but the resulting stream can now be coded without
+ // error. We take advantage of the fact that x264 buffers frame
+ // data internally to feed the same image into the encoder multiple
+ // times, just changing its start & stop times each time.
+ int64_t orig_stop = in->stop;
+ int64_t new_stop = in->start;
+ hb_buffer_t *last_buf = NULL;
+
+ // We want to spread the new frames uniformly over the total time
+ // so that we don't end up with a very short frame at the end.
+ // In the number of pieces calculation we add in init_delay-1 to
+ // round up but not add an extra piece if the frame duration is
+ // a multiple of init_delay. The final increment of frame_dur is
+ // to restore the bits that got truncated by the divide on the
+ // previous line. If we don't do this we end up with an extra tiny
+ // frame at the end whose duration is npieces-1.
+ int64_t frame_dur = orig_stop - new_stop;
+ int64_t npieces = ( frame_dur + pv->init_delay - 1 ) / pv->init_delay;
+ frame_dur /= npieces;
+ ++frame_dur;
+
+ while ( in->start < orig_stop )
+ {
+ new_stop += frame_dur;
+ if ( new_stop > orig_stop )
+ new_stop = orig_stop;
+ in->stop = new_stop;
+ hb_buffer_t *buf = x264_encode( w, in );
+ if ( buf )
+ {
+ if ( last_buf == NULL )
+ *buf_out = buf;
+ else
+ last_buf->next = buf;
+ last_buf = buf;
+ }
+ in->start = new_stop;
+ }
+ }
+ else
+ {
+ *buf_out = x264_encode( w, in );
+ }
+ return HB_WORK_OK;
+}
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