/*
  * MOV, 3GP, MP4 muxer RTP hinting
  * Copyright (c) 2010 Martin Storsjo
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "movenc.h"
 #include "libavutil/intreadwrite.h"

 #include "internal.h"

 #include "rtpenc_chain.h"

 #include "avio_internal.h"

 #include "rtp.h"

 
 int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
 {
     MOVMuxContext *mov  = s->priv_data;
     MOVTrack *track     = &mov->tracks[index];
     MOVTrack *src_track = &mov->tracks[src_index];
     AVStream *src_st    = s->streams[src_index];
     int ret = AVERROR(ENOMEM);
 
     track->tag = MKTAG('r','t','p',' ');
     track->src_track = src_index;
 

     track->enc = avcodec_alloc_context3(NULL);

     if (!track->enc)
         goto fail;
     track->enc->codec_type = AVMEDIA_TYPE_DATA;
     track->enc->codec_tag  = track->tag;
 

     ret = ff_rtp_chain_mux_open(&track->rtp_ctx, s, src_st, NULL,

                                 RTP_MAX_PACKET_SIZE, src_index);

     if (ret < 0)

         goto fail;
 
     /* Copy the RTP AVStream timebase back to the hint AVStream */
     track->timescale = track->rtp_ctx->streams[0]->time_base.den;
 
     /* Mark the hinted track that packets written to it should be
      * sent to this track for hinting. */
     src_track->hint_track = index;
     return 0;
 fail:
     av_log(s, AV_LOG_WARNING,
            "Unable to initialize hinting of stream %d\n", src_index);
     av_freep(&track->enc);

     /* Set a default timescale, to avoid crashes in av_dump_format */

     track->timescale = 90000;
     return ret;
 }
 

 /**
  * Remove the first sample from the sample queue.
  */
 static void sample_queue_pop(HintSampleQueue *queue)
 {
     if (queue->len <= 0)
         return;
     if (queue->samples[0].own_data)
         av_free(queue->samples[0].data);
     queue->len--;
     memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
 }
 
 /**
  * Empty the sample queue, releasing all memory.
  */
 static void sample_queue_free(HintSampleQueue *queue)
 {
     int i;
     for (i = 0; i < queue->len; i++)
         if (queue->samples[i].own_data)
             av_free(queue->samples[i].data);
     av_freep(&queue->samples);

     queue->len  = 0;

     queue->size = 0;
 }
 
 /**
  * Add a reference to the sample data to the sample queue. The data is
  * not copied. sample_queue_retain should be called before pkt->data
  * is reused/freed.
  */

 static void sample_queue_push(HintSampleQueue *queue, uint8_t *data, int size,
                               int sample)

 {
     /* No need to keep track of smaller samples, since describing them
      * with immediates is more efficient. */

     if (size <= 14)

         return;
     if (!queue->samples || queue->len >= queue->size) {

         HintSample *samples;

         samples = av_realloc_array(queue->samples, queue->size + 10, sizeof(HintSample));

         if (!samples)

             return;

         queue->size += 10;

         queue->samples = samples;

     }

     queue->samples[queue->len].data = data;
     queue->samples[queue->len].size = size;

     queue->samples[queue->len].sample_number = sample;

     queue->samples[queue->len].offset   = 0;

     queue->samples[queue->len].own_data = 0;
     queue->len++;
 }
 
 /**
  * Make local copies of all referenced sample data in the queue.
  */
 static void sample_queue_retain(HintSampleQueue *queue)
 {
     int i;
     for (i = 0; i < queue->len; ) {
         HintSample *sample = &queue->samples[i];
         if (!sample->own_data) {

             uint8_t *ptr = av_malloc(sample->size);

             if (!ptr) {
                 /* Unable to allocate memory for this one, remove it */
                 memmove(queue->samples + i, queue->samples + i + 1,
                         sizeof(HintSample)*(queue->len - i - 1));
                 queue->len--;
                 continue;
             }
             memcpy(ptr, sample->data, sample->size);
             sample->data = ptr;
             sample->own_data = 1;
         }
         i++;
     }
 }
 
 /**
  * Find matches of needle[n_pos ->] within haystack. If a sufficiently
  * large match is found, matching bytes before n_pos are included
  * in the match, too (within the limits of the arrays).
  *
  * @param haystack buffer that may contain parts of needle
  * @param h_len length of the haystack buffer
  * @param needle buffer containing source data that have been used to
  *               construct haystack
  * @param n_pos start position in needle used for looking for matches
  * @param n_len length of the needle buffer
  * @param match_h_offset_ptr offset of the first matching byte within haystack
  * @param match_n_offset_ptr offset of the first matching byte within needle
  * @param match_len_ptr length of the matched segment
  * @return 0 if a match was found, < 0 if no match was found
  */
 static int match_segments(const uint8_t *haystack, int h_len,
                           const uint8_t *needle, int n_pos, int n_len,
                           int *match_h_offset_ptr, int *match_n_offset_ptr,
                           int *match_len_ptr)
 {
     int h_pos;
     for (h_pos = 0; h_pos < h_len; h_pos++) {
         int match_len = 0;
         int match_h_pos, match_n_pos;
 
         /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
         while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
                needle[n_pos + match_len] == haystack[h_pos + match_len])
             match_len++;
         if (match_len <= 8)
             continue;
 
         /* If a sufficiently large match was found, try to expand
          * the matched segment backwards. */
         match_h_pos = h_pos;
         match_n_pos = n_pos;
         while (match_n_pos > 0 && match_h_pos > 0 &&
                needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
             match_n_pos--;
             match_h_pos--;
             match_len++;
         }
         if (match_len <= 14)
             continue;
         *match_h_offset_ptr = match_h_pos;
         *match_n_offset_ptr = match_n_pos;
         *match_len_ptr = match_len;
         return 0;
     }
     return -1;
 }
 
 /**
  * Look for segments in samples in the sample queue matching the data
  * in ptr. Samples not matching are removed from the queue. If a match
  * is found, the next time it will look for matches starting from the
  * end of the previous matched segment.
  *
  * @param data data to find matches for in the sample queue
  * @param len length of the data buffer
  * @param queue samples used for looking for matching segments
  * @param pos the offset in data of the matched segment
  * @param match_sample the number of the sample that contained the match
  * @param match_offset the offset of the matched segment within the sample
  * @param match_len the length of the matched segment
  * @return 0 if a match was found, < 0 if no match was found
  */
 static int find_sample_match(const uint8_t *data, int len,
                              HintSampleQueue *queue, int *pos,
                              int *match_sample, int *match_offset,
                              int *match_len)
 {
     while (queue->len > 0) {
         HintSample *sample = &queue->samples[0];
         /* If looking for matches in a new sample, skip the first 5 bytes,
          * since they often may be modified/removed in the output packet. */
         if (sample->offset == 0 && sample->size > 5)
             sample->offset = 5;
 
         if (match_segments(data, len, sample->data, sample->offset,
                            sample->size, pos, match_offset, match_len) == 0) {
             *match_sample = sample->sample_number;
             /* Next time, look for matches at this offset, with a little
              * margin to this match. */
             sample->offset = *match_offset + *match_len + 5;
             if (sample->offset + 10 >= sample->size)
                 sample_queue_pop(queue); /* Not enough useful data left */
             return 0;
         }
 
         if (sample->offset < 10 && sample->size > 20) {
             /* No match found from the start of the sample,
              * try from the middle of the sample instead. */
             sample->offset = sample->size/2;
         } else {
             /* No match for this sample, remove it */
             sample_queue_pop(queue);
         }
     }
     return -1;
 }
 

 static void output_immediate(const uint8_t *data, int size,

                              AVIOContext *out, int *entries)

 {
     while (size > 0) {
         int len = size;
         if (len > 14)
             len = 14;

         avio_w8(out, 1); /* immediate constructor */
         avio_w8(out, len); /* amount of valid data */
         avio_write(out, data, len);

         data += len;
         size -= len;
 
         for (; len < 14; len++)

             avio_w8(out, 0);

 
         (*entries)++;
     }
 }
 

 static void output_match(AVIOContext *out, int match_sample,

                          int match_offset, int match_len, int *entries)
 {

     avio_w8(out, 2); /* sample constructor */
     avio_w8(out, 0); /* track reference */
     avio_wb16(out, match_len);
     avio_wb32(out, match_sample);
     avio_wb32(out, match_offset);
     avio_wb16(out, 1); /* bytes per block */
     avio_wb16(out, 1); /* samples per block */

     (*entries)++;
 }
 

 static void describe_payload(const uint8_t *data, int size,

                              AVIOContext *out, int *entries,

                              HintSampleQueue *queue)

 {
     /* Describe the payload using different constructors */

     while (size > 0) {
         int match_sample, match_offset, match_len, pos;
         if (find_sample_match(data, size, queue, &pos, &match_sample,
                               &match_offset, &match_len) < 0)
             break;
         output_immediate(data, pos, out, entries);
         data += pos;
         size -= pos;
         output_match(out, match_sample, match_offset, match_len, entries);
         data += match_len;
         size -= match_len;
     }

     output_immediate(data, size, out, entries);
 }
 
 /**
  * Write an RTP hint (that may contain one or more RTP packets)
  * for the packets in data. data contains one or more packets with a
  * BE32 size header.
  *
  * @param out buffer where the hints are written
  * @param data buffer containing RTP packets
  * @param size the size of the data buffer
  * @param trk the MOVTrack for the hint track

  * @param dts pointer where the timestamp for the written RTP hint is stored

  * @return the number of RTP packets in the written hint
  */

 static int write_hint_packets(AVIOContext *out, const uint8_t *data,

                               int size, MOVTrack *trk, int64_t *dts)

 {
     int64_t curpos;
     int64_t count_pos, entries_pos;
     int count = 0, entries;
 

     count_pos = avio_tell(out);

     /* RTPsample header */

     avio_wb16(out, 0); /* packet count */
     avio_wb16(out, 0); /* reserved */

 
     while (size > 4) {
         uint32_t packet_len = AV_RB32(data);
         uint16_t seq;
         uint32_t ts;

         int32_t  ts_diff;

 
         data += 4;
         size -= 4;
         if (packet_len > size || packet_len <= 12)
             break;

         if (RTP_PT_IS_RTCP(data[1])) {

             /* RTCP packet, just skip */
             data += packet_len;
             size -= packet_len;
             continue;
         }
 
         if (packet_len > trk->max_packet_size)
             trk->max_packet_size = packet_len;
 
         seq = AV_RB16(&data[2]);

         ts  = AV_RB32(&data[4]);

 
         if (trk->prev_rtp_ts == 0)
             trk->prev_rtp_ts = ts;
         /* Unwrap the 32-bit RTP timestamp that wraps around often
          * into a not (as often) wrapping 64-bit timestamp. */

         ts_diff = ts - trk->prev_rtp_ts;
         if (ts_diff > 0) {
             trk->cur_rtp_ts_unwrapped += ts_diff;
             trk->prev_rtp_ts = ts;
             ts_diff = 0;
         }

         if (*dts == AV_NOPTS_VALUE)
             *dts = trk->cur_rtp_ts_unwrapped;

 
         count++;
         /* RTPpacket header */

         avio_wb32(out, 0); /* relative_time */
         avio_write(out, data, 2); /* RTP header */
         avio_wb16(out, seq); /* RTPsequenceseed */

         avio_wb16(out, ts_diff ? 4 : 0); /* reserved + flags (extra_flag) */

         entries_pos = avio_tell(out);

         avio_wb16(out, 0); /* entry count */

         if (ts_diff) { /* if extra_flag is set */
             avio_wb32(out, 16); /* extra_information_length */
             avio_wb32(out, 12); /* rtpoffsetTLV box */
             avio_write(out, "rtpo", 4);
             avio_wb32(out, ts_diff);
         }

 
         data += 12;
         size -= 12;
         packet_len -= 12;
 
         entries = 0;
         /* Write one or more constructors describing the payload data */

         describe_payload(data, packet_len, out, &entries, &trk->sample_queue);

         data += packet_len;
         size -= packet_len;
 

         curpos = avio_tell(out);

         avio_seek(out, entries_pos, SEEK_SET);

         avio_wb16(out, entries);

         avio_seek(out, curpos, SEEK_SET);

     }
 

     curpos = avio_tell(out);

     avio_seek(out, count_pos, SEEK_SET);

     avio_wb16(out, count);

     avio_seek(out, curpos, SEEK_SET);

     return count;
 }
 
 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,

                              int track_index, int sample,
                              uint8_t *sample_data, int sample_size)

 {
     MOVMuxContext *mov = s->priv_data;
     MOVTrack *trk = &mov->tracks[track_index];
     AVFormatContext *rtp_ctx = trk->rtp_ctx;
     uint8_t *buf = NULL;
     int size;

     AVIOContext *hintbuf = NULL;

     AVPacket hint_pkt;
     int ret = 0, count;
 
     if (!rtp_ctx)
         return AVERROR(ENOENT);
     if (!rtp_ctx->pb)
         return AVERROR(ENOMEM);
 

     if (sample_data)
         sample_queue_push(&trk->sample_queue, sample_data, sample_size, sample);
     else
         sample_queue_push(&trk->sample_queue, pkt->data, pkt->size, sample);

     /* Feed the packet to the RTP muxer */

     ff_write_chained(rtp_ctx, 0, pkt, s);

 
     /* Fetch the output from the RTP muxer, open a new output buffer
      * for next time. */

     size = avio_close_dyn_buf(rtp_ctx->pb, &buf);

     if ((ret = ffio_open_dyn_packet_buf(&rtp_ctx->pb,

                                         RTP_MAX_PACKET_SIZE)) < 0)

         goto done;
 
     if (size <= 0)
         goto done;
 
     /* Open a buffer for writing the hint */

     if ((ret = avio_open_dyn_buf(&hintbuf)) < 0)

         goto done;
     av_init_packet(&hint_pkt);
     count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
     av_freep(&buf);
 
     /* Write the hint data into the hint track */

     hint_pkt.size = size = avio_close_dyn_buf(hintbuf, &buf);

     hint_pkt.data = buf;
     hint_pkt.pts  = hint_pkt.dts;
     hint_pkt.stream_index = track_index;
     if (pkt->flags & AV_PKT_FLAG_KEY)
         hint_pkt.flags |= AV_PKT_FLAG_KEY;
     if (count > 0)
         ff_mov_write_packet(s, &hint_pkt);
 done:
     av_free(buf);

     sample_queue_retain(&trk->sample_queue);

     return ret;
 }
 

 void ff_mov_close_hinting(MOVTrack *track)
 {
     AVFormatContext *rtp_ctx = track->rtp_ctx;

     uint8_t *ptr;
 
     av_freep(&track->enc);

     sample_queue_free(&track->sample_queue);

     if (!rtp_ctx)
         return;
     if (rtp_ctx->pb) {
         av_write_trailer(rtp_ctx);

         avio_close_dyn_buf(rtp_ctx->pb, &ptr);

         av_free(ptr);
     }

     avformat_free_context(rtp_ctx);

 }