FFmpeg/avconv_filter.c

/*
 * avconv filter configuration
 *
 * 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
 */

#include <stdint.h>

#include "avconv.h"

#include "libavfilter/avfilter.h"
#include "libavfilter/buffersrc.h"

#include "libavresample/avresample.h"

#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/display.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "libavutil/pixfmt.h"
#include "libavutil/samplefmt.h"

/* Define a function for building a string containing a list of
 * allowed formats. */
#define DEF_CHOOSE_FORMAT(suffix, type, var, supported_list, none, get_name)   \
static char *choose_ ## suffix (OutputFilter *ofilter)                         \
{                                                                              \
    if (ofilter->var != none) {                                                \
        get_name(ofilter->var);                                                \
        return av_strdup(name);                                                \
    } else if (ofilter->supported_list) {                                      \
        const type *p;                                                         \
        AVIOContext *s = NULL;                                                 \
        uint8_t *ret;                                                          \
        int len;                                                               \
                                                                               \
        if (avio_open_dyn_buf(&s) < 0)                                         \
            exit(1);                                                           \
                                                                               \
        for (p = ofilter->supported_list; *p != none; p++) {                   \
            get_name(*p);                                                      \
            avio_printf(s, "%s|", name);                                       \
        }                                                                      \
        len = avio_close_dyn_buf(s, &ret);                                     \
        ret[len - 1] = 0;                                                      \
        return ret;                                                            \
    } else                                                                     \
        return NULL;                                                           \
}

DEF_CHOOSE_FORMAT(pix_fmts, enum AVPixelFormat, format, formats, AV_PIX_FMT_NONE,
                  GET_PIX_FMT_NAME)

DEF_CHOOSE_FORMAT(sample_fmts, enum AVSampleFormat, format, formats,
                  AV_SAMPLE_FMT_NONE, GET_SAMPLE_FMT_NAME)

DEF_CHOOSE_FORMAT(sample_rates, int, sample_rate, sample_rates, 0,
                  GET_SAMPLE_RATE_NAME)

DEF_CHOOSE_FORMAT(channel_layouts, uint64_t, channel_layout, channel_layouts, 0,
                  GET_CH_LAYOUT_NAME)

int init_simple_filtergraph(InputStream *ist, OutputStream *ost)
{
    FilterGraph *fg = av_mallocz(sizeof(*fg));

    if (!fg)
        exit(1);
    fg->index = nb_filtergraphs;

    GROW_ARRAY(fg->outputs, fg->nb_outputs);
    if (!(fg->outputs[0] = av_mallocz(sizeof(*fg->outputs[0]))))
        exit(1);
    fg->outputs[0]->ost   = ost;
    fg->outputs[0]->graph = fg;
    fg->outputs[0]->format = -1;

    ost->filter = fg->outputs[0];

    GROW_ARRAY(fg->inputs, fg->nb_inputs);
    if (!(fg->inputs[0] = av_mallocz(sizeof(*fg->inputs[0]))))
        exit(1);
    fg->inputs[0]->ist   = ist;
    fg->inputs[0]->graph = fg;
    fg->inputs[0]->format = -1;

    fg->inputs[0]->frame_queue = av_fifo_alloc(8 * sizeof(AVFrame*));
    if (!fg->inputs[0])
        exit_program(1);

    GROW_ARRAY(ist->filters, ist->nb_filters);
    ist->filters[ist->nb_filters - 1] = fg->inputs[0];

    GROW_ARRAY(filtergraphs, nb_filtergraphs);
    filtergraphs[nb_filtergraphs - 1] = fg;

    return 0;
}

static void init_input_filter(FilterGraph *fg, AVFilterInOut *in)
{
    InputStream *ist = NULL;
    enum AVMediaType type = avfilter_pad_get_type(in->filter_ctx->input_pads, in->pad_idx);
    int i;

    // TODO: support other filter types
    if (type != AVMEDIA_TYPE_VIDEO && type != AVMEDIA_TYPE_AUDIO) {
        av_log(NULL, AV_LOG_FATAL, "Only video and audio filters supported "
               "currently.\n");
        exit(1);
    }

    if (in->name) {
        AVFormatContext *s;
        AVStream       *st = NULL;
        char *p;
        int file_idx = strtol(in->name, &p, 0);

        if (file_idx < 0 || file_idx >= nb_input_files) {
            av_log(NULL, AV_LOG_FATAL, "Invalid file index %d in filtegraph description %s.\n",
                   file_idx, fg->graph_desc);
            exit(1);
        }
        s = input_files[file_idx]->ctx;

        for (i = 0; i < s->nb_streams; i++) {
            if (s->streams[i]->codecpar->codec_type != type)
                continue;
            if (check_stream_specifier(s, s->streams[i], *p == ':' ? p + 1 : p) == 1) {
                st = s->streams[i];
                break;
            }
        }
        if (!st) {
            av_log(NULL, AV_LOG_FATAL, "Stream specifier '%s' in filtergraph description %s "
                   "matches no streams.\n", p, fg->graph_desc);
            exit(1);
        }
        ist = input_streams[input_files[file_idx]->ist_index + st->index];
    } else {
        /* find the first unused stream of corresponding type */
        for (i = 0; i < nb_input_streams; i++) {
            ist = input_streams[i];
            if (ist->dec_ctx->codec_type == type && ist->discard)
                break;
        }
        if (i == nb_input_streams) {
            av_log(NULL, AV_LOG_FATAL, "Cannot find a matching stream for "
                   "unlabeled input pad %d on filter %s\n", in->pad_idx,
                   in->filter_ctx->name);
            exit(1);
        }
    }
    av_assert0(ist);

    ist->discard         = 0;
    ist->decoding_needed = 1;
    ist->st->discard = AVDISCARD_NONE;

    GROW_ARRAY(fg->inputs, fg->nb_inputs);
    if (!(fg->inputs[fg->nb_inputs - 1] = av_mallocz(sizeof(*fg->inputs[0]))))
        exit(1);
    fg->inputs[fg->nb_inputs - 1]->ist   = ist;
    fg->inputs[fg->nb_inputs - 1]->graph = fg;
    fg->inputs[fg->nb_inputs - 1]->format = -1;

    fg->inputs[fg->nb_inputs - 1]->frame_queue = av_fifo_alloc(8 * sizeof(AVFrame*));
    if (!fg->inputs[fg->nb_inputs - 1])
        exit_program(1);

    GROW_ARRAY(ist->filters, ist->nb_filters);
    ist->filters[ist->nb_filters - 1] = fg->inputs[fg->nb_inputs - 1];
}

int init_complex_filtergraph(FilterGraph *fg)
{
    AVFilterInOut *inputs, *outputs, *cur;
    AVFilterGraph *graph;
    int ret = 0;

    /* this graph is only used for determining the kinds of inputs
     * and outputs we have, and is discarded on exit from this function */
    graph = avfilter_graph_alloc();
    if (!graph)
        return AVERROR(ENOMEM);

    ret = avfilter_graph_parse2(graph, fg->graph_desc, &inputs, &outputs);
    if (ret < 0)
        goto fail;

    for (cur = inputs; cur; cur = cur->next)
        init_input_filter(fg, cur);

    for (cur = outputs; cur;) {
        GROW_ARRAY(fg->outputs, fg->nb_outputs);
        fg->outputs[fg->nb_outputs - 1] = av_mallocz(sizeof(*fg->outputs[0]));
        if (!fg->outputs[fg->nb_outputs - 1])
            exit(1);

        fg->outputs[fg->nb_outputs - 1]->graph   = fg;
        fg->outputs[fg->nb_outputs - 1]->out_tmp = cur;
        fg->outputs[fg->nb_outputs - 1]->type    = avfilter_pad_get_type(cur->filter_ctx->output_pads,
                                                                         cur->pad_idx);
        cur = cur->next;
        fg->outputs[fg->nb_outputs - 1]->out_tmp->next = NULL;
    }

fail:
    avfilter_inout_free(&inputs);
    avfilter_graph_free(&graph);
    return ret;
}

static int insert_trim(int64_t start_time, int64_t duration,
                       AVFilterContext **last_filter, int *pad_idx,
                       const char *filter_name)
{
    AVFilterGraph *graph = (*last_filter)->graph;
    AVFilterContext *ctx;
    const AVFilter *trim;
    enum AVMediaType type = avfilter_pad_get_type((*last_filter)->output_pads, *pad_idx);
    const char *name = (type == AVMEDIA_TYPE_VIDEO) ? "trim" : "atrim";
    int ret = 0;

    if (duration == INT64_MAX && start_time == AV_NOPTS_VALUE)
        return 0;

    trim = avfilter_get_by_name(name);
    if (!trim) {
        av_log(NULL, AV_LOG_ERROR, "%s filter not present, cannot limit "
               "recording time.\n", name);
        return AVERROR_FILTER_NOT_FOUND;
    }

    ctx = avfilter_graph_alloc_filter(graph, trim, filter_name);
    if (!ctx)
        return AVERROR(ENOMEM);

    if (duration != INT64_MAX) {
        ret = av_opt_set_double(ctx, "duration", (double)duration / 1e6,
                                AV_OPT_SEARCH_CHILDREN);
    }
    if (ret >= 0 && start_time != AV_NOPTS_VALUE) {
        ret = av_opt_set_double(ctx, "start", (double)start_time / 1e6,
                                AV_OPT_SEARCH_CHILDREN);
    }
    if (ret < 0) {
        av_log(ctx, AV_LOG_ERROR, "Error configuring the %s filter", name);
        return ret;
    }

    ret = avfilter_init_str(ctx, NULL);
    if (ret < 0)
        return ret;

    ret = avfilter_link(*last_filter, *pad_idx, ctx, 0);
    if (ret < 0)
        return ret;

    *last_filter = ctx;
    *pad_idx     = 0;
    return 0;
}

static int insert_filter(AVFilterContext **last_filter, int *pad_idx,
                         const char *filter_name, const char *args)
{
    AVFilterGraph *graph = (*last_filter)->graph;
    AVFilterContext *ctx;
    int ret;

    ret = avfilter_graph_create_filter(&ctx,
                                       avfilter_get_by_name(filter_name),
                                       filter_name, args, NULL, graph);
    if (ret < 0)
        return ret;

    ret = avfilter_link(*last_filter, *pad_idx, ctx, 0);
    if (ret < 0)
        return ret;

    *last_filter = ctx;
    *pad_idx     = 0;
    return 0;
}

static int configure_output_video_filter(FilterGraph *fg, OutputFilter *ofilter, AVFilterInOut *out)
{
    char *pix_fmts;
    OutputStream *ost = ofilter->ost;
    OutputFile    *of = output_files[ost->file_index];
    AVFilterContext *last_filter = out->filter_ctx;
    int pad_idx = out->pad_idx;
    int ret;
    char name[255];

    snprintf(name, sizeof(name), "output stream %d:%d", ost->file_index, ost->index);
    ret = avfilter_graph_create_filter(&ofilter->filter,
                                       avfilter_get_by_name("buffersink"),
                                       name, NULL, NULL, fg->graph);
    if (ret < 0)
        return ret;

    if (!hw_device_ctx && (ofilter->width || ofilter->height)) {
        char args[255];
        AVFilterContext *filter;

        snprintf(args, sizeof(args), "%d:%d:0x%X",
                 ofilter->width, ofilter->height,
                 (unsigned)ost->sws_flags);
        snprintf(name, sizeof(name), "scaler for output stream %d:%d",
                 ost->file_index, ost->index);
        if ((ret = avfilter_graph_create_filter(&filter, avfilter_get_by_name("scale"),
                                                name, args, NULL, fg->graph)) < 0)
            return ret;
        if ((ret = avfilter_link(last_filter, pad_idx, filter, 0)) < 0)
            return ret;

        last_filter = filter;
        pad_idx = 0;
    }

    if ((pix_fmts = choose_pix_fmts(ofilter))) {
        AVFilterContext *filter;
        snprintf(name, sizeof(name), "pixel format for output stream %d:%d",
                 ost->file_index, ost->index);
        ret = avfilter_graph_create_filter(&filter,
                                           avfilter_get_by_name("format"),
                                           "format", pix_fmts, NULL, fg->graph);
        av_freep(&pix_fmts);
        if (ret < 0)
            return ret;
        if ((ret = avfilter_link(last_filter, pad_idx, filter, 0)) < 0)
            return ret;

        last_filter = filter;
        pad_idx     = 0;
    }

    if (ost->frame_rate.num) {
        AVFilterContext *fps;
        char args[255];

        snprintf(args, sizeof(args), "fps=%d/%d", ost->frame_rate.num,
                 ost->frame_rate.den);
        snprintf(name, sizeof(name), "fps for output stream %d:%d",
                 ost->file_index, ost->index);
        ret = avfilter_graph_create_filter(&fps, avfilter_get_by_name("fps"),
                                           name, args, NULL, fg->graph);
        if (ret < 0)
            return ret;

        ret = avfilter_link(last_filter, pad_idx, fps, 0);
        if (ret < 0)
            return ret;
        last_filter = fps;
        pad_idx = 0;
    }

    snprintf(name, sizeof(name), "trim for output stream %d:%d",
             ost->file_index, ost->index);
    ret = insert_trim(of->start_time, of->recording_time,
                      &last_filter, &pad_idx, name);
    if (ret < 0)
        return ret;


    if ((ret = avfilter_link(last_filter, pad_idx, ofilter->filter, 0)) < 0)
        return ret;

    return 0;
}

static int configure_output_audio_filter(FilterGraph *fg, OutputFilter *ofilter, AVFilterInOut *out)
{
    OutputStream *ost = ofilter->ost;
    OutputFile    *of = output_files[ost->file_index];
    AVCodecContext *codec  = ost->enc_ctx;
    AVFilterContext *last_filter = out->filter_ctx;
    int pad_idx = out->pad_idx;
    char *sample_fmts, *sample_rates, *channel_layouts;
    char name[255];
    int ret;


    snprintf(name, sizeof(name), "output stream %d:%d", ost->file_index, ost->index);
    ret = avfilter_graph_create_filter(&ofilter->filter,
                                       avfilter_get_by_name("abuffersink"),
                                       name, NULL, NULL, fg->graph);
    if (ret < 0)
        return ret;

    if (codec->channels && !codec->channel_layout)
        codec->channel_layout = av_get_default_channel_layout(codec->channels);

    sample_fmts     = choose_sample_fmts(ofilter);
    sample_rates    = choose_sample_rates(ofilter);
    channel_layouts = choose_channel_layouts(ofilter);
    if (sample_fmts || sample_rates || channel_layouts) {
        AVFilterContext *format;
        char args[256];
        int len = 0;

        if (sample_fmts)
            len += snprintf(args + len, sizeof(args) - len, "sample_fmts=%s:",
                            sample_fmts);
        if (sample_rates)
            len += snprintf(args + len, sizeof(args) - len, "sample_rates=%s:",
                            sample_rates);
        if (channel_layouts)
            len += snprintf(args + len, sizeof(args) - len, "channel_layouts=%s:",
                            channel_layouts);
        args[len - 1] = 0;

        av_freep(&sample_fmts);
        av_freep(&sample_rates);
        av_freep(&channel_layouts);

        snprintf(name, sizeof(name), "audio format for output stream %d:%d",
                 ost->file_index, ost->index);
        ret = avfilter_graph_create_filter(&format,
                                           avfilter_get_by_name("aformat"),
                                           name, args, NULL, fg->graph);
        if (ret < 0)
            return ret;

        ret = avfilter_link(last_filter, pad_idx, format, 0);
        if (ret < 0)
            return ret;

        last_filter = format;
        pad_idx = 0;
    }

    snprintf(name, sizeof(name), "trim for output stream %d:%d",
             ost->file_index, ost->index);
    ret = insert_trim(of->start_time, of->recording_time,
                      &last_filter, &pad_idx, name);
    if (ret < 0)
        return ret;

    if ((ret = avfilter_link(last_filter, pad_idx, ofilter->filter, 0)) < 0)
        return ret;

    return 0;
}

#define DESCRIBE_FILTER_LINK(f, inout, in)                         \
{                                                                  \
    AVFilterContext *ctx = inout->filter_ctx;                      \
    AVFilterPad *pads = in ? ctx->input_pads  : ctx->output_pads;  \
    int       nb_pads = in ? ctx->nb_inputs   : ctx->nb_outputs;   \
    AVIOContext *pb;                                               \
                                                                   \
    if (avio_open_dyn_buf(&pb) < 0)                                \
        exit(1);                                                   \
                                                                   \
    avio_printf(pb, "%s", ctx->filter->name);                      \
    if (nb_pads > 1)                                               \
        avio_printf(pb, ":%s", avfilter_pad_get_name(pads, inout->pad_idx));\
    avio_w8(pb, 0);                                                \
    avio_close_dyn_buf(pb, &f->name);                              \
}

int configure_output_filter(FilterGraph *fg, OutputFilter *ofilter, AVFilterInOut *out)
{
    av_freep(&ofilter->name);
    DESCRIBE_FILTER_LINK(ofilter, out, 0);

    switch (avfilter_pad_get_type(out->filter_ctx->output_pads, out->pad_idx)) {
    case AVMEDIA_TYPE_VIDEO: return configure_output_video_filter(fg, ofilter, out);
    case AVMEDIA_TYPE_AUDIO: return configure_output_audio_filter(fg, ofilter, out);
    default: av_assert0(0);
    }
}

static int configure_input_video_filter(FilterGraph *fg, InputFilter *ifilter,
                                        AVFilterInOut *in)
{
    AVFilterContext *last_filter;
    const AVFilter *buffer_filt = avfilter_get_by_name("buffer");
    InputStream *ist = ifilter->ist;
    InputFile     *f = input_files[ist->file_index];
    AVRational tb = ist->framerate.num ? av_inv_q(ist->framerate) :
                                         ist->st->time_base;
    AVBufferSrcParameters *par;
    char name[255];
    int ret, pad_idx = 0;

    snprintf(name, sizeof(name), "graph %d input from stream %d:%d", fg->index,
             ist->file_index, ist->st->index);

    ifilter->filter = avfilter_graph_alloc_filter(fg->graph, buffer_filt, name);
    if (!ifilter->filter)
        return AVERROR(ENOMEM);

    par = av_buffersrc_parameters_alloc();
    if (!par)
        return AVERROR(ENOMEM);

    par->sample_aspect_ratio = ifilter->sample_aspect_ratio;
    par->width               = ifilter->width;
    par->height              = ifilter->height;
    par->format              = ifilter->format;
    par->time_base           = tb;
    par->hw_frames_ctx       = ifilter->hw_frames_ctx;

    ret = av_buffersrc_parameters_set(ifilter->filter, par);
    av_freep(&par);
    if (ret < 0)
        return ret;

    ret = avfilter_init_str(ifilter->filter, NULL);
    if (ret < 0)
        return ret;

    last_filter = ifilter->filter;

    if (ist->autorotate) {
        uint8_t* displaymatrix = av_stream_get_side_data(ist->st,
                                                         AV_PKT_DATA_DISPLAYMATRIX, NULL);
        if (displaymatrix) {
            double rot = av_display_rotation_get((int32_t*) displaymatrix);
            if (rot < -135 || rot > 135) {
                ret = insert_filter(&last_filter, &pad_idx, "vflip", NULL);
                if (ret < 0)
                    return ret;
                ret = insert_filter(&last_filter, &pad_idx, "hflip", NULL);
            } else if (rot < -45) {
                ret = insert_filter(&last_filter, &pad_idx, "transpose", "dir=clock");
            } else if (rot > 45) {
                ret = insert_filter(&last_filter, &pad_idx, "transpose", "dir=cclock");
            }
            if (ret < 0)
                return ret;
        }
    }

    if (ist->framerate.num) {
        AVFilterContext *setpts;

        snprintf(name, sizeof(name), "force CFR for input from stream %d:%d",
                 ist->file_index, ist->st->index);
        if ((ret = avfilter_graph_create_filter(&setpts,
                                                avfilter_get_by_name("setpts"),
                                                name, "N", NULL,
                                                fg->graph)) < 0)
            return ret;

        if ((ret = avfilter_link(last_filter, 0, setpts, 0)) < 0)
            return ret;

        last_filter = setpts;
    }

    snprintf(name, sizeof(name), "trim for input stream %d:%d",
             ist->file_index, ist->st->index);
    ret = insert_trim(((f->start_time == AV_NOPTS_VALUE) || !f->accurate_seek) ?
                      AV_NOPTS_VALUE : 0, f->recording_time, &last_filter, &pad_idx, name);
    if (ret < 0)
        return ret;

    if ((ret = avfilter_link(last_filter, 0, in->filter_ctx, in->pad_idx)) < 0)
        return ret;
    return 0;
}

static int configure_input_audio_filter(FilterGraph *fg, InputFilter *ifilter,
                                        AVFilterInOut *in)
{
    AVFilterContext *last_filter;
    const AVFilter *abuffer_filt = avfilter_get_by_name("abuffer");
    InputStream *ist = ifilter->ist;
    InputFile     *f = input_files[ist->file_index];
    AVBufferSrcParameters *par;
    char args[255], name[255];
    int ret, pad_idx = 0;

    snprintf(name, sizeof(name), "graph %d input from stream %d:%d", fg->index,
             ist->file_index, ist->st->index);

    ifilter->filter = avfilter_graph_alloc_filter(fg->graph, abuffer_filt, name);
    if (!ifilter->filter)
        return AVERROR(ENOMEM);

    par = av_buffersrc_parameters_alloc();
    if (!par)
        return AVERROR(ENOMEM);

    par->time_base      = (AVRational){ 1, ifilter->sample_rate };
    par->sample_rate    = ifilter->sample_rate;
    par->format         = ifilter->format;
    par->channel_layout = ifilter->channel_layout;

    ret = av_buffersrc_parameters_set(ifilter->filter, par);
    av_freep(&par);
    if (ret < 0)
        return ret;

    ret = avfilter_init_str(ifilter->filter, NULL);
    if (ret < 0)
        return ret;
    last_filter = ifilter->filter;

    if (audio_sync_method > 0) {
        AVFilterContext *async;
        int  len = 0;

        av_log(NULL, AV_LOG_WARNING, "-async has been deprecated. Used the "
               "asyncts audio filter instead.\n");

        if (audio_sync_method > 1)
            len += snprintf(args + len, sizeof(args) - len, "compensate=1:"
                            "max_comp=%d:", audio_sync_method);
        snprintf(args + len, sizeof(args) - len, "min_delta=%f",
                 audio_drift_threshold);

        snprintf(name, sizeof(name), "graph %d audio sync for input stream %d:%d",
                 fg->index, ist->file_index, ist->st->index);
        ret = avfilter_graph_create_filter(&async,
                                           avfilter_get_by_name("asyncts"),
                                           name, args, NULL, fg->graph);
        if (ret < 0)
            return ret;

        ret = avfilter_link(last_filter, 0, async, 0);
        if (ret < 0)
            return ret;

        last_filter = async;
    }
    if (audio_volume != 256) {
        AVFilterContext *volume;

        av_log(NULL, AV_LOG_WARNING, "-vol has been deprecated. Use the volume "
               "audio filter instead.\n");

        snprintf(args, sizeof(args), "volume=%f", audio_volume / 256.0);

        snprintf(name, sizeof(name), "graph %d volume for input stream %d:%d",
                 fg->index, ist->file_index, ist->st->index);
        ret = avfilter_graph_create_filter(&volume,
                                           avfilter_get_by_name("volume"),
                                           name, args, NULL, fg->graph);
        if (ret < 0)
            return ret;

        ret = avfilter_link(last_filter, 0, volume, 0);
        if (ret < 0)
            return ret;

        last_filter = volume;
    }

    snprintf(name, sizeof(name), "trim for input stream %d:%d",
             ist->file_index, ist->st->index);
    ret = insert_trim(((f->start_time == AV_NOPTS_VALUE) || !f->accurate_seek) ?
                      AV_NOPTS_VALUE : 0, f->recording_time, &last_filter, &pad_idx, name);
    if (ret < 0)
        return ret;

    if ((ret = avfilter_link(last_filter, 0, in->filter_ctx, in->pad_idx)) < 0)
        return ret;

    return 0;
}

static int configure_input_filter(FilterGraph *fg, InputFilter *ifilter,
                                  AVFilterInOut *in)
{
    av_freep(&ifilter->name);
    DESCRIBE_FILTER_LINK(ifilter, in, 1);

    switch (avfilter_pad_get_type(in->filter_ctx->input_pads, in->pad_idx)) {
    case AVMEDIA_TYPE_VIDEO: return configure_input_video_filter(fg, ifilter, in);
    case AVMEDIA_TYPE_AUDIO: return configure_input_audio_filter(fg, ifilter, in);
    default: av_assert0(0);
    }
}

int configure_filtergraph(FilterGraph *fg)
{
    AVFilterInOut *inputs, *outputs, *cur;
    int ret, i, simple = filtergraph_is_simple(fg);
    const char *graph_desc = simple ? fg->outputs[0]->ost->avfilter :
                                      fg->graph_desc;

    avfilter_graph_free(&fg->graph);
    if (!(fg->graph = avfilter_graph_alloc()))
        return AVERROR(ENOMEM);

    if (simple) {
        OutputStream *ost = fg->outputs[0]->ost;
        char args[512];
        AVDictionaryEntry *e = NULL;

        snprintf(args, sizeof(args), "flags=0x%X", (unsigned)ost->sws_flags);
        fg->graph->scale_sws_opts = av_strdup(args);

        args[0] = '\0';
        while ((e = av_dict_get(fg->outputs[0]->ost->resample_opts, "", e,
                                AV_DICT_IGNORE_SUFFIX))) {
            av_strlcatf(args, sizeof(args), "%s=%s:", e->key, e->value);
        }
        if (strlen(args))
            args[strlen(args) - 1] = '\0';
        fg->graph->resample_lavr_opts = av_strdup(args);
    }

    if ((ret = avfilter_graph_parse2(fg->graph, graph_desc, &inputs, &outputs)) < 0)
        return ret;

    if (hw_device_ctx) {
        for (i = 0; i < fg->graph->nb_filters; i++) {
            fg->graph->filters[i]->hw_device_ctx = av_buffer_ref(hw_device_ctx);
        }
    }

    if (simple && (!inputs || inputs->next || !outputs || outputs->next)) {
        av_log(NULL, AV_LOG_ERROR, "Simple filtergraph '%s' does not have "
               "exactly one input and output.\n", graph_desc);
        return AVERROR(EINVAL);
    }

    for (cur = inputs, i = 0; cur; cur = cur->next, i++)
        if ((ret = configure_input_filter(fg, fg->inputs[i], cur)) < 0)
            return ret;
    avfilter_inout_free(&inputs);

    for (cur = outputs, i = 0; cur; cur = cur->next, i++) {
        OutputFilter *ofilter = fg->outputs[i];
        if (ofilter->ost)
            configure_output_filter(fg, ofilter, cur);
    }

    avfilter_inout_free(&outputs);

    if ((ret = avfilter_graph_config(fg->graph, NULL)) < 0)
        return ret;

    /* limit the lists of allowed formats to the ones selected, to
     * make sure they stay the same if the filtergraph is reconfigured later */
    for (i = 0; i < fg->nb_outputs; i++) {
        OutputFilter *ofilter = fg->outputs[i];
        AVFilterLink *link = ofilter->filter->inputs[0];

        ofilter->format = link->format;

        ofilter->width  = link->w;
        ofilter->height = link->h;

        ofilter->sample_rate    = link->sample_rate;
        ofilter->channel_layout = link->channel_layout;
    }

    return 0;
}

int ifilter_parameters_from_frame(InputFilter *ifilter, const AVFrame *frame)
{
    av_buffer_unref(&ifilter->hw_frames_ctx);

    ifilter->format = frame->format;

    ifilter->width               = frame->width;
    ifilter->height              = frame->height;
    ifilter->sample_aspect_ratio = frame->sample_aspect_ratio;

    ifilter->sample_rate         = frame->sample_rate;
    ifilter->channel_layout      = frame->channel_layout;

    if (frame->hw_frames_ctx) {
        ifilter->hw_frames_ctx = av_buffer_ref(frame->hw_frames_ctx);
        if (!ifilter->hw_frames_ctx)
            return AVERROR(ENOMEM);
    }

    return 0;
}

int ist_in_filtergraph(FilterGraph *fg, InputStream *ist)
{
    int i;
    for (i = 0; i < fg->nb_inputs; i++)
        if (fg->inputs[i]->ist == ist)
            return 1;
    return 0;
}

int filtergraph_is_simple(FilterGraph *fg)
{
    return !fg->graph_desc;
}