h264: rename h264.[ch] to h264dec.[ch]

This is more consistent with the naming of other decoders.

1 files changed, 982 insertions, 0 deletions

diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c
new file mode 100644
index 0000000000..6eb2da8665
--- /dev/null
+++ b/libavcodec/h264dec.c
@@ -0,0 +1,982 @@
+/*
+ * H.26L/H.264/AVC/JVT/14496-10/... decoder
+ * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * H.264 / AVC / MPEG-4 part10 codec.
+ * @author Michael Niedermayer <michaelni@gmx.at>
+ */
+
+#include "libavutil/display.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+#include "libavutil/stereo3d.h"
+#include "libavutil/timer.h"
+#include "internal.h"
+#include "bytestream.h"
+#include "cabac.h"
+#include "cabac_functions.h"
+#include "error_resilience.h"
+#include "avcodec.h"
+#include "h264dec.h"
+#include "h2645_parse.h"
+#include "h264data.h"
+#include "h264chroma.h"
+#include "h264_mvpred.h"
+#include "golomb.h"
+#include "mathops.h"
+#include "me_cmp.h"
+#include "mpegutils.h"
+#include "profiles.h"
+#include "rectangle.h"
+#include "thread.h"
+
+#include <assert.h>
+
+const uint16_t ff_h264_mb_sizes[4] = { 256, 384, 512, 768 };
+
+static void h264_er_decode_mb(void *opaque, int ref, int mv_dir, int mv_type,
+                              int (*mv)[2][4][2],
+                              int mb_x, int mb_y, int mb_intra, int mb_skipped)
+{
+    H264Context *h = opaque;
+    H264SliceContext *sl = &h->slice_ctx[0];
+
+    sl->mb_x = mb_x;
+    sl->mb_y = mb_y;
+    sl->mb_xy = mb_x + mb_y * h->mb_stride;
+    memset(sl->non_zero_count_cache, 0, sizeof(sl->non_zero_count_cache));
+    assert(ref >= 0);
+    /* FIXME: It is possible albeit uncommon that slice references
+     * differ between slices. We take the easy approach and ignore
+     * it for now. If this turns out to have any relevance in
+     * practice then correct remapping should be added. */
+    if (ref >= sl->ref_count[0])
+        ref = 0;
+    fill_rectangle(&h->cur_pic.ref_index[0][4 * sl->mb_xy],
+                   2, 2, 2, ref, 1);
+    fill_rectangle(&sl->ref_cache[0][scan8[0]], 4, 4, 8, ref, 1);
+    fill_rectangle(sl->mv_cache[0][scan8[0]], 4, 4, 8,
+                   pack16to32((*mv)[0][0][0], (*mv)[0][0][1]), 4);
+    assert(!FRAME_MBAFF(h));
+    ff_h264_hl_decode_mb(h, &h->slice_ctx[0]);
+}
+
+void ff_h264_draw_horiz_band(const H264Context *h, H264SliceContext *sl,
+                             int y, int height)
+{
+    AVCodecContext *avctx = h->avctx;
+    const AVFrame   *src  = h->cur_pic.f;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
+    int vshift = desc->log2_chroma_h;
+    const int field_pic = h->picture_structure != PICT_FRAME;
+    if (field_pic) {
+        height <<= 1;
+        y      <<= 1;
+    }
+
+    height = FFMIN(height, avctx->height - y);
+
+    if (field_pic && h->first_field && !(avctx->slice_flags & SLICE_FLAG_ALLOW_FIELD))
+        return;
+
+    if (avctx->draw_horiz_band) {
+        int offset[AV_NUM_DATA_POINTERS];
+        int i;
+
+        offset[0] = y * src->linesize[0];
+        offset[1] =
+        offset[2] = (y >> vshift) * src->linesize[1];
+        for (i = 3; i < AV_NUM_DATA_POINTERS; i++)
+            offset[i] = 0;
+
+        emms_c();
+
+        avctx->draw_horiz_band(avctx, src, offset,
+                               y, h->picture_structure, height);
+    }
+}
+
+void ff_h264_free_tables(H264Context *h)
+{
+    int i;
+
+    av_freep(&h->intra4x4_pred_mode);
+    av_freep(&h->chroma_pred_mode_table);
+    av_freep(&h->cbp_table);
+    av_freep(&h->mvd_table[0]);
+    av_freep(&h->mvd_table[1]);
+    av_freep(&h->direct_table);
+    av_freep(&h->non_zero_count);
+    av_freep(&h->slice_table_base);
+    h->slice_table = NULL;
+    av_freep(&h->list_counts);
+
+    av_freep(&h->mb2b_xy);
+    av_freep(&h->mb2br_xy);
+
+    av_buffer_pool_uninit(&h->qscale_table_pool);
+    av_buffer_pool_uninit(&h->mb_type_pool);
+    av_buffer_pool_uninit(&h->motion_val_pool);
+    av_buffer_pool_uninit(&h->ref_index_pool);
+
+    for (i = 0; i < h->nb_slice_ctx; i++) {
+        H264SliceContext *sl = &h->slice_ctx[i];
+
+        av_freep(&sl->dc_val_base);
+        av_freep(&sl->er.mb_index2xy);
+        av_freep(&sl->er.error_status_table);
+        av_freep(&sl->er.er_temp_buffer);
+
+        av_freep(&sl->bipred_scratchpad);
+        av_freep(&sl->edge_emu_buffer);
+        av_freep(&sl->top_borders[0]);
+        av_freep(&sl->top_borders[1]);
+
+        sl->bipred_scratchpad_allocated = 0;
+        sl->edge_emu_buffer_allocated   = 0;
+        sl->top_borders_allocated[0]    = 0;
+        sl->top_borders_allocated[1]    = 0;
+    }
+}
+
+int ff_h264_alloc_tables(H264Context *h)
+{
+    const int big_mb_num = h->mb_stride * (h->mb_height + 1);
+    const int row_mb_num = h->mb_stride * 2 * h->nb_slice_ctx;
+    int x, y;
+
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->intra4x4_pred_mode,
+                      row_mb_num * 8 * sizeof(uint8_t), fail)
+    h->slice_ctx[0].intra4x4_pred_mode = h->intra4x4_pred_mode;
+
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->non_zero_count,
+                      big_mb_num * 48 * sizeof(uint8_t), fail)
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->slice_table_base,
+                      (big_mb_num + h->mb_stride) * sizeof(*h->slice_table_base), fail)
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->cbp_table,
+                      big_mb_num * sizeof(uint16_t), fail)
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->chroma_pred_mode_table,
+                      big_mb_num * sizeof(uint8_t), fail)
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->mvd_table[0],
+                      16 * row_mb_num * sizeof(uint8_t), fail);
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->mvd_table[1],
+                      16 * row_mb_num * sizeof(uint8_t), fail);
+    h->slice_ctx[0].mvd_table[0] = h->mvd_table[0];
+    h->slice_ctx[0].mvd_table[1] = h->mvd_table[1];
+
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->direct_table,
+                      4 * big_mb_num * sizeof(uint8_t), fail);
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->list_counts,
+                      big_mb_num * sizeof(uint8_t), fail)
+
+    memset(h->slice_table_base, -1,
+           (big_mb_num + h->mb_stride) * sizeof(*h->slice_table_base));
+    h->slice_table = h->slice_table_base + h->mb_stride * 2 + 1;
+
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->mb2b_xy,
+                      big_mb_num * sizeof(uint32_t), fail);
+    FF_ALLOCZ_OR_GOTO(h->avctx, h->mb2br_xy,
+                      big_mb_num * sizeof(uint32_t), fail);
+    for (y = 0; y < h->mb_height; y++)
+        for (x = 0; x < h->mb_width; x++) {
+            const int mb_xy = x + y * h->mb_stride;
+            const int b_xy  = 4 * x + 4 * y * h->b_stride;
+
+            h->mb2b_xy[mb_xy]  = b_xy;
+            h->mb2br_xy[mb_xy] = 8 * (FMO ? mb_xy : (mb_xy % (2 * h->mb_stride)));
+        }
+
+    return 0;
+
+fail:
+    ff_h264_free_tables(h);
+    return AVERROR(ENOMEM);
+}
+
+/**
+ * Init context
+ * Allocate buffers which are not shared amongst multiple threads.
+ */
+int ff_h264_slice_context_init(H264Context *h, H264SliceContext *sl)
+{
+    ERContext *er = &sl->er;
+    int mb_array_size = h->mb_height * h->mb_stride;
+    int y_size  = (2 * h->mb_width + 1) * (2 * h->mb_height + 1);
+    int c_size  = h->mb_stride * (h->mb_height + 1);
+    int yc_size = y_size + 2   * c_size;
+    int x, y, i;
+
+    sl->ref_cache[0][scan8[5]  + 1] =
+    sl->ref_cache[0][scan8[7]  + 1] =
+    sl->ref_cache[0][scan8[13] + 1] =
+    sl->ref_cache[1][scan8[5]  + 1] =
+    sl->ref_cache[1][scan8[7]  + 1] =
+    sl->ref_cache[1][scan8[13] + 1] = PART_NOT_AVAILABLE;
+
+    if (CONFIG_ERROR_RESILIENCE) {
+        /* init ER */
+        er->avctx          = h->avctx;
+        er->decode_mb      = h264_er_decode_mb;
+        er->opaque         = h;
+        er->quarter_sample = 1;
+
+        er->mb_num      = h->mb_num;
+        er->mb_width    = h->mb_width;
+        er->mb_height   = h->mb_height;
+        er->mb_stride   = h->mb_stride;
+        er->b8_stride   = h->mb_width * 2 + 1;
+
+        // error resilience code looks cleaner with this
+        FF_ALLOCZ_OR_GOTO(h->avctx, er->mb_index2xy,
+                          (h->mb_num + 1) * sizeof(int), fail);
+
+        for (y = 0; y < h->mb_height; y++)
+            for (x = 0; x < h->mb_width; x++)
+                er->mb_index2xy[x + y * h->mb_width] = x + y * h->mb_stride;
+
+        er->mb_index2xy[h->mb_height * h->mb_width] = (h->mb_height - 1) *
+                                                      h->mb_stride + h->mb_width;
+
+        FF_ALLOCZ_OR_GOTO(h->avctx, er->error_status_table,
+                          mb_array_size * sizeof(uint8_t), fail);
+
+        FF_ALLOC_OR_GOTO(h->avctx, er->er_temp_buffer,
+                         h->mb_height * h->mb_stride, fail);
+
+        FF_ALLOCZ_OR_GOTO(h->avctx, sl->dc_val_base,
+                          yc_size * sizeof(int16_t), fail);
+        er->dc_val[0] = sl->dc_val_base + h->mb_width * 2 + 2;
+        er->dc_val[1] = sl->dc_val_base + y_size + h->mb_stride + 1;
+        er->dc_val[2] = er->dc_val[1] + c_size;
+        for (i = 0; i < yc_size; i++)
+            sl->dc_val_base[i] = 1024;
+    }
+
+    return 0;
+
+fail:
+    return AVERROR(ENOMEM); // ff_h264_free_tables will clean up for us
+}
+
+static int h264_init_context(AVCodecContext *avctx, H264Context *h)
+{
+    int i;
+
+    h->avctx                 = avctx;
+
+    h->picture_structure     = PICT_FRAME;
+    h->workaround_bugs       = avctx->workaround_bugs;
+    h->flags                 = avctx->flags;
+    h->poc.prev_poc_msb      = 1 << 16;
+    h->recovery_frame        = -1;
+    h->frame_recovered       = 0;
+
+    h->next_outputed_poc = INT_MIN;
+    for (i = 0; i < MAX_DELAYED_PIC_COUNT; i++)
+        h->last_pocs[i] = INT_MIN;
+
+    ff_h264_sei_uninit(&h->sei);
+
+    avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;
+
+    h->nb_slice_ctx = (avctx->active_thread_type & FF_THREAD_SLICE) ? avctx->thread_count : 1;
+    h->slice_ctx = av_mallocz_array(h->nb_slice_ctx, sizeof(*h->slice_ctx));
+    if (!h->slice_ctx) {
+        h->nb_slice_ctx = 0;
+        return AVERROR(ENOMEM);
+    }
+
+    for (i = 0; i < H264_MAX_PICTURE_COUNT; i++) {
+        h->DPB[i].f = av_frame_alloc();
+        if (!h->DPB[i].f)
+            return AVERROR(ENOMEM);
+    }
+
+    h->cur_pic.f = av_frame_alloc();
+    if (!h->cur_pic.f)
+        return AVERROR(ENOMEM);
+
+    for (i = 0; i < h->nb_slice_ctx; i++)
+        h->slice_ctx[i].h264 = h;
+
+    return 0;
+}
+
+static av_cold int h264_decode_end(AVCodecContext *avctx)
+{
+    H264Context *h = avctx->priv_data;
+    int i;
+
+    ff_h264_free_tables(h);
+
+    for (i = 0; i < H264_MAX_PICTURE_COUNT; i++) {
+        ff_h264_unref_picture(h, &h->DPB[i]);
+        av_frame_free(&h->DPB[i].f);
+    }
+
+    h->cur_pic_ptr = NULL;
+
+    av_freep(&h->slice_ctx);
+    h->nb_slice_ctx = 0;
+
+    for (i = 0; i < MAX_SPS_COUNT; i++)
+        av_buffer_unref(&h->ps.sps_list[i]);
+
+    for (i = 0; i < MAX_PPS_COUNT; i++)
+        av_buffer_unref(&h->ps.pps_list[i]);
+
+    ff_h2645_packet_uninit(&h->pkt);
+
+    ff_h264_unref_picture(h, &h->cur_pic);
+    av_frame_free(&h->cur_pic.f);
+
+    return 0;
+}
+
+static AVOnce h264_vlc_init = AV_ONCE_INIT;
+
+av_cold int ff_h264_decode_init(AVCodecContext *avctx)
+{
+    H264Context *h = avctx->priv_data;
+    int ret;
+
+    ret = h264_init_context(avctx, h);
+    if (ret < 0)
+        return ret;
+
+    ret = ff_thread_once(&h264_vlc_init, ff_h264_decode_init_vlc);
+    if (ret != 0) {
+        av_log(avctx, AV_LOG_ERROR, "pthread_once has failed.");
+        return AVERROR_UNKNOWN;
+    }
+
+    if (avctx->codec_id == AV_CODEC_ID_H264) {
+        if (avctx->ticks_per_frame == 1)
+            h->avctx->framerate.num *= 2;
+        avctx->ticks_per_frame = 2;
+    }
+
+    if (avctx->extradata_size > 0 && avctx->extradata) {
+       ret = ff_h264_decode_extradata(avctx->extradata, avctx->extradata_size,
+                                      &h->ps, &h->is_avc, &h->nal_length_size,
+                                      avctx->err_recognition, avctx);
+       if (ret < 0) {
+           h264_decode_end(avctx);
+           return ret;
+       }
+    }
+
+    if (h->ps.sps && h->ps.sps->bitstream_restriction_flag &&
+        h->avctx->has_b_frames < h->ps.sps->num_reorder_frames) {
+        h->avctx->has_b_frames = h->ps.sps->num_reorder_frames;
+    }
+
+    avctx->internal->allocate_progress = 1;
+
+    if (h->enable_er) {
+        av_log(avctx, AV_LOG_WARNING,
+               "Error resilience is enabled. It is unsafe and unsupported and may crash. "
+               "Use it at your own risk\n");
+    }
+
+    return 0;
+}
+
+static int decode_init_thread_copy(AVCodecContext *avctx)
+{
+    H264Context *h = avctx->priv_data;
+    int ret;
+
+    if (!avctx->internal->is_copy)
+        return 0;
+
+    memset(h, 0, sizeof(*h));
+
+    ret = h264_init_context(avctx, h);
+    if (ret < 0)
+        return ret;
+
+    h->context_initialized = 0;
+
+    return 0;
+}
+
+/**
+ * Run setup operations that must be run after slice header decoding.
+ * This includes finding the next displayed frame.
+ *
+ * @param h h264 master context
+ * @param setup_finished enough NALs have been read that we can call
+ * ff_thread_finish_setup()
+ */
+static void decode_postinit(H264Context *h, int setup_finished)
+{
+    const SPS *sps = h->ps.sps;
+    H264Picture *out = h->cur_pic_ptr;
+    H264Picture *cur = h->cur_pic_ptr;
+    int i, pics, out_of_order, out_idx;
+    int invalid = 0, cnt = 0;
+
+    if (h->next_output_pic)
+        return;
+
+    if (cur->field_poc[0] == INT_MAX || cur->field_poc[1] == INT_MAX) {
+        /* FIXME: if we have two PAFF fields in one packet, we can't start
+         * the next thread here. If we have one field per packet, we can.
+         * The check in decode_nal_units() is not good enough to find this
+         * yet, so we assume the worst for now. */
+        // if (setup_finished)
+        //    ff_thread_finish_setup(h->avctx);
+        return;
+    }
+
+    // FIXME do something with unavailable reference frames
+
+    /* Sort B-frames into display order */
+    if (sps->bitstream_restriction_flag ||
+        h->avctx->strict_std_compliance >= FF_COMPLIANCE_NORMAL) {
+        h->avctx->has_b_frames = FFMAX(h->avctx->has_b_frames, sps->num_reorder_frames);
+    }
+
+    pics = 0;
+    while (h->delayed_pic[pics])
+        pics++;
+
+    assert(pics <= MAX_DELAYED_PIC_COUNT);
+
+    h->delayed_pic[pics++] = cur;
+    if (cur->reference == 0)
+        cur->reference = DELAYED_PIC_REF;
+
+    /* Frame reordering. This code takes pictures from coding order and sorts
+     * them by their incremental POC value into display order. It supports POC
+     * gaps, MMCO reset codes and random resets.
+     * A "display group" can start either with a IDR frame (f.key_frame = 1),
+     * and/or can be closed down with a MMCO reset code. In sequences where
+     * there is no delay, we can't detect that (since the frame was already
+     * output to the user), so we also set h->mmco_reset to detect the MMCO
+     * reset code.
+     * FIXME: if we detect insufficient delays (as per h->avctx->has_b_frames),
+     * we increase the delay between input and output. All frames affected by
+     * the lag (e.g. those that should have been output before another frame
+     * that we already returned to the user) will be dropped. This is a bug
+     * that we will fix later. */
+    for (i = 0; i < MAX_DELAYED_PIC_COUNT; i++) {
+        cnt     += out->poc < h->last_pocs[i];
+        invalid += out->poc == INT_MIN;
+    }
+    if (!h->mmco_reset && !cur->f->key_frame &&
+        cnt + invalid == MAX_DELAYED_PIC_COUNT && cnt > 0) {
+        h->mmco_reset = 2;
+        if (pics > 1)
+            h->delayed_pic[pics - 2]->mmco_reset = 2;
+    }
+    if (h->mmco_reset || cur->f->key_frame) {
+        for (i = 0; i < MAX_DELAYED_PIC_COUNT; i++)
+            h->last_pocs[i] = INT_MIN;
+        cnt     = 0;
+        invalid = MAX_DELAYED_PIC_COUNT;
+    }
+    out     = h->delayed_pic[0];
+    out_idx = 0;
+    for (i = 1; i < MAX_DELAYED_PIC_COUNT &&
+                h->delayed_pic[i] &&
+                !h->delayed_pic[i - 1]->mmco_reset &&
+                !h->delayed_pic[i]->f->key_frame;
+         i++)
+        if (h->delayed_pic[i]->poc < out->poc) {
+            out     = h->delayed_pic[i];
+            out_idx = i;
+        }
+    if (h->avctx->has_b_frames == 0 &&
+        (h->delayed_pic[0]->f->key_frame || h->mmco_reset))
+        h->next_outputed_poc = INT_MIN;
+    out_of_order = !out->f->key_frame && !h->mmco_reset &&
+                   (out->poc < h->next_outputed_poc);
+
+    if (sps->bitstream_restriction_flag &&
+        h->avctx->has_b_frames >= sps->num_reorder_frames) {
+    } else if (out_of_order && pics - 1 == h->avctx->has_b_frames &&
+               h->avctx->has_b_frames < MAX_DELAYED_PIC_COUNT) {
+        if (invalid + cnt < MAX_DELAYED_PIC_COUNT) {
+            h->avctx->has_b_frames = FFMAX(h->avctx->has_b_frames, cnt);
+        }
+    } else if (!h->avctx->has_b_frames &&
+               ((h->next_outputed_poc != INT_MIN &&
+                 out->poc > h->next_outputed_poc + 2) ||
+                cur->f->pict_type == AV_PICTURE_TYPE_B)) {
+        h->avctx->has_b_frames++;
+    }
+
+    if (pics > h->avctx->has_b_frames) {
+        out->reference &= ~DELAYED_PIC_REF;
+        for (i = out_idx; h->delayed_pic[i]; i++)
+            h->delayed_pic[i] = h->delayed_pic[i + 1];
+    }
+    memmove(h->last_pocs, &h->last_pocs[1],
+            sizeof(*h->last_pocs) * (MAX_DELAYED_PIC_COUNT - 1));
+    h->last_pocs[MAX_DELAYED_PIC_COUNT - 1] = cur->poc;
+    if (!out_of_order && pics > h->avctx->has_b_frames) {
+        h->next_output_pic = out;
+        if (out->mmco_reset) {
+            if (out_idx > 0) {
+                h->next_outputed_poc                    = out->poc;
+                h->delayed_pic[out_idx - 1]->mmco_reset = out->mmco_reset;
+            } else {
+                h->next_outputed_poc = INT_MIN;
+            }
+        } else {
+            if (out_idx == 0 && pics > 1 && h->delayed_pic[0]->f->key_frame) {
+                h->next_outputed_poc = INT_MIN;
+            } else {
+                h->next_outputed_poc = out->poc;
+            }
+        }
+        h->mmco_reset = 0;
+    } else {
+        av_log(h->avctx, AV_LOG_DEBUG, "no picture\n");
+    }
+
+    if (h->next_output_pic) {
+        if (h->next_output_pic->recovered) {
+            // We have reached an recovery point and all frames after it in
+            // display order are "recovered".
+            h->frame_recovered |= FRAME_RECOVERED_SEI;
+        }
+        h->next_output_pic->recovered |= !!(h->frame_recovered & FRAME_RECOVERED_SEI);
+    }
+
+    if (setup_finished && !h->avctx->hwaccel) {
+        ff_thread_finish_setup(h->avctx);
+
+        if (h->avctx->active_thread_type & FF_THREAD_FRAME)
+            h->setup_finished = 1;
+    }
+}
+
+/**
+ * instantaneous decoder refresh.
+ */
+static void idr(H264Context *h)
+{
+    ff_h264_remove_all_refs(h);
+    h->poc.prev_frame_num        =
+    h->poc.prev_frame_num_offset =
+    h->poc.prev_poc_msb          =
+    h->poc.prev_poc_lsb          = 0;
+}
+
+/* forget old pics after a seek */
+void ff_h264_flush_change(H264Context *h)
+{
+    int i;
+    for (i = 0; i < MAX_DELAYED_PIC_COUNT; i++)
+        h->last_pocs[i] = INT_MIN;
+    h->next_outputed_poc = INT_MIN;
+    h->prev_interlaced_frame = 1;
+    idr(h);
+    if (h->cur_pic_ptr)
+        h->cur_pic_ptr->reference = 0;
+    h->first_field = 0;
+    ff_h264_sei_uninit(&h->sei);
+    h->recovery_frame = -1;
+    h->frame_recovered = 0;
+}
+
+/* forget old pics after a seek */
+static void flush_dpb(AVCodecContext *avctx)
+{
+    H264Context *h = avctx->priv_data;
+    int i;
+
+    memset(h->delayed_pic, 0, sizeof(h->delayed_pic));
+
+    ff_h264_flush_change(h);
+
+    for (i = 0; i < H264_MAX_PICTURE_COUNT; i++)
+        ff_h264_unref_picture(h, &h->DPB[i]);
+    h->cur_pic_ptr = NULL;
+    ff_h264_unref_picture(h, &h->cur_pic);
+
+    h->mb_y = 0;
+
+    ff_h264_free_tables(h);
+    h->context_initialized = 0;
+}
+
+static int get_last_needed_nal(H264Context *h)
+{
+    int nals_needed = 0;
+    int i;
+
+    for (i = 0; i < h->pkt.nb_nals; i++) {
+        H2645NAL *nal = &h->pkt.nals[i];
+        GetBitContext gb;
+
+        /* packets can sometimes contain multiple PPS/SPS,
+         * e.g. two PAFF field pictures in one packet, or a demuxer
+         * which splits NALs strangely if so, when frame threading we
+         * can't start the next thread until we've read all of them */
+        switch (nal->type) {
+        case NAL_SPS:
+        case NAL_PPS:
+            nals_needed = i;
+            break;
+        case NAL_DPA:
+        case NAL_IDR_SLICE:
+        case NAL_SLICE:
+            init_get_bits(&gb, nal->data + 1, (nal->size - 1) * 8);
+            if (!get_ue_golomb(&gb))
+                nals_needed = i;
+        }
+    }
+
+    return nals_needed;
+}
+
+static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
+{
+    AVCodecContext *const avctx = h->avctx;
+    unsigned context_count = 0;
+    int nals_needed = 0; ///< number of NALs that need decoding before the next frame thread starts
+    int i, ret = 0;
+
+    if (!(avctx->flags2 & AV_CODEC_FLAG2_CHUNKS)) {
+        h->current_slice = 0;
+        if (!h->first_field)
+            h->cur_pic_ptr = NULL;
+        ff_h264_sei_uninit(&h->sei);
+    }
+
+    ret = ff_h2645_packet_split(&h->pkt, buf, buf_size, avctx, h->is_avc,
+                                h->nal_length_size, avctx->codec_id);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR,
+               "Error splitting the input into NAL units.\n");
+        return ret;
+    }
+
+    if (avctx->active_thread_type & FF_THREAD_FRAME)
+        nals_needed = get_last_needed_nal(h);
+
+    for (i = 0; i < h->pkt.nb_nals; i++) {
+        H2645NAL *nal = &h->pkt.nals[i];
+        H264SliceContext *sl = &h->slice_ctx[context_count];
+        int err;
+
+        if (avctx->skip_frame >= AVDISCARD_NONREF &&
+            nal->ref_idc == 0 && nal->type != NAL_SEI)
+            continue;
+
+        // FIXME these should stop being context-global variables
+        h->nal_ref_idc   = nal->ref_idc;
+        h->nal_unit_type = nal->type;
+
+        err = 0;
+        switch (nal->type) {
+        case NAL_IDR_SLICE:
+            if (nal->type != NAL_IDR_SLICE) {
+                av_log(h->avctx, AV_LOG_ERROR,
+                       "Invalid mix of idr and non-idr slices\n");
+                ret = -1;
+                goto end;
+            }
+            idr(h); // FIXME ensure we don't lose some frames if there is reordering
+        case NAL_SLICE:
+            sl->gb = nal->gb;
+
+            if ((err = ff_h264_decode_slice_header(h, sl, nal)))
+                break;
+
+            if (h->sei.recovery_point.recovery_frame_cnt >= 0 && h->recovery_frame < 0) {
+                h->recovery_frame = (h->poc.frame_num + h->sei.recovery_point.recovery_frame_cnt) &
+                                    ((1 << h->ps.sps->log2_max_frame_num) - 1);
+            }
+
+            h->cur_pic_ptr->f->key_frame |=
+                (nal->type == NAL_IDR_SLICE) || (h->sei.recovery_point.recovery_frame_cnt >= 0);
+
+            if (nal->type == NAL_IDR_SLICE || h->recovery_frame == h->poc.frame_num) {
+                h->recovery_frame         = -1;
+                h->cur_pic_ptr->recovered = 1;
+            }
+            // If we have an IDR, all frames after it in decoded order are
+            // "recovered".
+            if (nal->type == NAL_IDR_SLICE)
+                h->frame_recovered |= FRAME_RECOVERED_IDR;
+            h->cur_pic_ptr->recovered |= !!(h->frame_recovered & FRAME_RECOVERED_IDR);
+
+            if (h->current_slice == 1) {
+                if (!(avctx->flags2 & AV_CODEC_FLAG2_CHUNKS))
+                    decode_postinit(h, i >= nals_needed);
+
+                if (h->avctx->hwaccel &&
+                    (ret = h->avctx->hwaccel->start_frame(h->avctx, NULL, 0)) < 0)
+                    return ret;
+            }
+
+            if (sl->redundant_pic_count == 0 &&
+                (avctx->skip_frame < AVDISCARD_NONREF || nal->ref_idc) &&
+                (avctx->skip_frame < AVDISCARD_BIDIR  ||
+                 sl->slice_type_nos != AV_PICTURE_TYPE_B) &&
+                (avctx->skip_frame < AVDISCARD_NONKEY ||
+                 h->cur_pic_ptr->f->key_frame) &&
+                avctx->skip_frame < AVDISCARD_ALL) {
+                if (avctx->hwaccel) {
+                    ret = avctx->hwaccel->decode_slice(avctx, nal->raw_data, nal->raw_size);
+                    if (ret < 0)
+                        return ret;
+                } else
+                    context_count++;
+            }
+            break;
+        case NAL_DPA:
+        case NAL_DPB:
+        case NAL_DPC:
+            avpriv_request_sample(avctx, "data partitioning");
+            ret = AVERROR(ENOSYS);
+            goto end;
+            break;
+        case NAL_SEI:
+            ret = ff_h264_sei_decode(&h->sei, &nal->gb, &h->ps, avctx);
+            if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
+                goto end;
+            break;
+        case NAL_SPS:
+            ret = ff_h264_decode_seq_parameter_set(&nal->gb, avctx, &h->ps);
+            if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
+                goto end;
+            break;
+        case NAL_PPS:
+            ret = ff_h264_decode_picture_parameter_set(&nal->gb, avctx, &h->ps,
+                                                       nal->size_bits);
+            if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
+                goto end;
+            break;
+        case NAL_AUD:
+        case NAL_END_SEQUENCE:
+        case NAL_END_STREAM:
+        case NAL_FILLER_DATA:
+        case NAL_SPS_EXT:
+        case NAL_AUXILIARY_SLICE:
+            break;
+        default:
+            av_log(avctx, AV_LOG_DEBUG, "Unknown NAL code: %d (%d bits)\n",
+                   nal->type, nal->size_bits);
+        }
+
+        if (context_count == h->nb_slice_ctx) {
+            ret = ff_h264_execute_decode_slices(h, context_count);
+            if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
+                goto end;
+            context_count = 0;
+        }
+
+        if (err < 0) {
+            av_log(h->avctx, AV_LOG_ERROR, "decode_slice_header error\n");
+            sl->ref_count[0] = sl->ref_count[1] = sl->list_count = 0;
+        }
+    }
+    if (context_count) {
+        ret = ff_h264_execute_decode_slices(h, context_count);
+        if (ret < 0 && (h->avctx->err_recognition & AV_EF_EXPLODE))
+            goto end;
+    }
+
+    ret = 0;
+end:
+    /* clean up */
+    if (h->cur_pic_ptr && !h->droppable) {
+        ff_thread_report_progress(&h->cur_pic_ptr->tf, INT_MAX,
+                                  h->picture_structure == PICT_BOTTOM_FIELD);
+    }
+
+    return (ret < 0) ? ret : buf_size;
+}
+
+/**
+ * Return the number of bytes consumed for building the current frame.
+ */
+static int get_consumed_bytes(int pos, int buf_size)
+{
+    if (pos == 0)
+        pos = 1;        // avoid infinite loops (I doubt that is needed but...)
+    if (pos + 10 > buf_size)
+        pos = buf_size; // oops ;)
+
+    return pos;
+}
+
+static int output_frame(H264Context *h, AVFrame *dst, AVFrame *src)
+{
+    int i;
+    int ret = av_frame_ref(dst, src);
+    if (ret < 0)
+        return ret;
+
+    if (!h->ps.sps || !h->ps.sps->crop)
+        return 0;
+
+    for (i = 0; i < 3; i++) {
+        int hshift = (i > 0) ? h->chroma_x_shift : 0;
+        int vshift = (i > 0) ? h->chroma_y_shift : 0;
+        int off    = ((h->ps.sps->crop_left >> hshift) << h->pixel_shift) +
+                     (h->ps.sps->crop_top >> vshift) * dst->linesize[i];
+        dst->data[i] += off;
+    }
+    return 0;
+}
+
+static int h264_decode_frame(AVCodecContext *avctx, void *data,
+                             int *got_frame, AVPacket *avpkt)
+{
+    const uint8_t *buf = avpkt->data;
+    int buf_size       = avpkt->size;
+    H264Context *h     = avctx->priv_data;
+    AVFrame *pict      = data;
+    int buf_index      = 0;
+    int ret;
+    const uint8_t *new_extradata;
+    int new_extradata_size;
+
+    h->flags = avctx->flags;
+    h->setup_finished = 0;
+
+    /* end of stream, output what is still in the buffers */
+out:
+    if (buf_size == 0) {
+        H264Picture *out;
+        int i, out_idx;
+
+        h->cur_pic_ptr = NULL;
+
+        // FIXME factorize this with the output code below
+        out     = h->delayed_pic[0];
+        out_idx = 0;
+        for (i = 1;
+             h->delayed_pic[i] &&
+             !h->delayed_pic[i]->f->key_frame &&
+             !h->delayed_pic[i]->mmco_reset;
+             i++)
+            if (h->delayed_pic[i]->poc < out->poc) {
+                out     = h->delayed_pic[i];
+                out_idx = i;
+            }
+
+        for (i = out_idx; h->delayed_pic[i]; i++)
+            h->delayed_pic[i] = h->delayed_pic[i + 1];
+
+        if (out) {
+            ret = output_frame(h, pict, out->f);
+            if (ret < 0)
+                return ret;
+            *got_frame = 1;
+        }
+
+        return buf_index;
+    }
+
+    new_extradata_size = 0;
+    new_extradata = av_packet_get_side_data(avpkt, AV_PKT_DATA_NEW_EXTRADATA,
+                                            &new_extradata_size);
+    if (new_extradata_size > 0 && new_extradata) {
+        ret = ff_h264_decode_extradata(new_extradata, new_extradata_size,
+                                       &h->ps, &h->is_avc, &h->nal_length_size,
+                                       avctx->err_recognition, avctx);
+        if (ret < 0)
+            return ret;
+    }
+
+    buf_index = decode_nal_units(h, buf, buf_size);
+    if (buf_index < 0)
+        return AVERROR_INVALIDDATA;
+
+    if (!h->cur_pic_ptr && h->nal_unit_type == NAL_END_SEQUENCE) {
+        buf_size = 0;
+        goto out;
+    }
+
+    if (!(avctx->flags2 & AV_CODEC_FLAG2_CHUNKS) && !h->cur_pic_ptr) {
+        if (avctx->skip_frame >= AVDISCARD_NONREF)
+            return 0;
+        av_log(avctx, AV_LOG_ERROR, "no frame!\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (!(avctx->flags2 & AV_CODEC_FLAG2_CHUNKS) ||
+        (h->mb_y >= h->mb_height && h->mb_height)) {
+        if (avctx->flags2 & AV_CODEC_FLAG2_CHUNKS)
+            decode_postinit(h, 1);
+
+        ff_h264_field_end(h, &h->slice_ctx[0], 0);
+
+        *got_frame = 0;
+        if (h->next_output_pic && ((avctx->flags & AV_CODEC_FLAG_OUTPUT_CORRUPT) ||
+                                   h->next_output_pic->recovered)) {
+            if (!h->next_output_pic->recovered)
+                h->next_output_pic->f->flags |= AV_FRAME_FLAG_CORRUPT;
+
+            ret = output_frame(h, pict, h->next_output_pic->f);
+            if (ret < 0)
+                return ret;
+            *got_frame = 1;
+        }
+    }
+
+    assert(pict->buf[0] || !*got_frame);
+
+    return get_consumed_bytes(buf_index, buf_size);
+}
+
+#define OFFSET(x) offsetof(H264Context, x)
+#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
+static const AVOption h264_options[] = {
+    { "enable_er", "Enable error resilience on damaged frames (unsafe)", OFFSET(enable_er), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, VD },
+    { NULL },
+};
+
+static const AVClass h264_class = {
+    .class_name = "h264",
+    .item_name  = av_default_item_name,
+    .option     = h264_options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVCodec ff_h264_decoder = {
+    .name                  = "h264",
+    .long_name             = NULL_IF_CONFIG_SMALL("H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"),
+    .type                  = AVMEDIA_TYPE_VIDEO,
+    .id                    = AV_CODEC_ID_H264,
+    .priv_data_size        = sizeof(H264Context),
+    .init                  = ff_h264_decode_init,
+    .close                 = h264_decode_end,
+    .decode                = h264_decode_frame,
+    .capabilities          = /*AV_CODEC_CAP_DRAW_HORIZ_BAND |*/ AV_CODEC_CAP_DR1 |
+                             AV_CODEC_CAP_DELAY | AV_CODEC_CAP_SLICE_THREADS |
+                             AV_CODEC_CAP_FRAME_THREADS,
+    .caps_internal         = FF_CODEC_CAP_INIT_THREADSAFE,
+    .flush                 = flush_dpb,
+    .init_thread_copy      = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
+    .update_thread_context = ONLY_IF_THREADS_ENABLED(ff_h264_update_thread_context),
+    .profiles              = NULL_IF_CONFIG_SMALL(ff_h264_profiles),
+    .priv_class            = &h264_class,
+};